Instant reproduction. An AI can "create offspring" very fast, by simply copying itself to any system to which it has access. Likewise, if the memories and knowledge obtained by the different AIs are in an easily transferable format, they can simply be copied, enabling computer systems to learn immense amounts of information in an instant.

Software self-improvement involves the computer studying itself and applying its intelligence to modifying itself to become more intelligent, then using that improved intelligence to modify itself further. An AI could make itself more intelligent by, for instance, studying its learning algorithms for signs of bias and improving them with better ones, developing ways for more effective management of its working memory, or creating entirely new program modules for handling particular tasks. Each round of improvement would make the AI smarter and accelerate continued self-improvement. An early, primitive example of this sort of capability was EURISKO, a computer program composed of different heuristics (rules of thumb) which it used for learning and for creating and modifying its own heuristics. Having been fed hundreds of pages of rules for the Traveller science fiction wargame, EURISKO began running simulated battles between different fleets of its own design, abstracting useful principles into new heuristics and modifying old ones with the help of its creator. When EURISKO was eventually entered into a tournament, the fleet of its design won the contest single-handedly. In response, the organizers of the contest revised the rules, releasing the new set of them only a short time before the next contest. According to the creator of the program, Douglas Lenat, the original EURISKO would not have had the time to design a new fleet in such a short time - but now it had learned enough general-purpose heuristics from the first contest that it could build a fleet that won the contest, even with the modified rules.

And it is much easier to improve a purely digital entity than it is to improve human beings: an electronic being can be built in a modular fashion and have bits of it re-written from scratch. The minds of human beings are evolved to be hopelessly interdependent and are so fragile that they easily develop numerous traumas and disorders even without outside tampering.

Further reading:
Why care about artificial intelligence?
Eurisko, The Computer With A Mind Of Its Own

Objection 11: "Friendliness" is too vaguely defined.

Answer: This is true, because Friendly AI is currently an open research subject. It's not that we don't know how it should be implemented, it's that we don't even know what exactly should be implemented. If anything, this is a reason to spend more resources studying the problem.

Some informal proposals for defining Friendliness do exist. The one that currently seems most promising is called Coherent Extrapolated Volition. In the CEV proposal, an AI will be built (or, to be exact, a proto-AI will be built to program another) to extrapolate what the ultimate desires of all the humans in the world would be if those humans knew everything a superintelligent being could potentially know; could think faster and smarter; were more like they wanted to be (more altruistic, more hard-working, whatever your ideal self is); would have lived with other humans for a longer time; had mainly those parts of themselves taken into account that they wanted to be taken into account. The ultimate desire - the volition - of everyone is extrapolated, with the AI then beginning to direct humanity towards a future where everyone's volitions are fulfilled in the best manner possible. The desirability of the different futures is weighted by the strength of humanity's desire - a smaller group of people with a very intense desire to see something happen may "overrule" a larger group who'd slightly prefer the opposite alternative but doesn't really care all that much either way. Humanity is not instantly "upgraded" to the ideal state, but instead gradually directed towards it.

CEV avoids the problem of its programmers having to define the wanted values exactly, as it draws them directly out of the minds of people. Likewise it avoids the problem of confusing ends with means, as it'll explictly model society's development and the development of different desires as well. Everybody who thinks their favorite political model happens to objectively be the best in the world for everyone should be happy to implement CEV - if it really turns out that it is the best one in the world, CEV will end up implementing it. (Likewise, if it is the best for humanity that an AI stays mostly out of its affairs, that will happen as well.) A perfect implementation of CEV is unbiased in the sense that it will produce the same kind of world regardless of who builds it, and regardless of what their ideology happens to be - assuming the builders are intelligent enough to avoid including their own empirical beliefs (aside for the bare minimum required for the mind to function) into the model, and trust that if they are correct, the AI will figure them out on its own.

Further reading:
Coherent Extrapolated Volition
Objections to Coherent Extrapolated Volition
Knowability of Friendly AI

Objection 12: What if the AI misinterprets its goals?

Answer: It is true that language and symbol systems are open to infinite interpretations, and an AI which has been given its goals purely in the form of written text may understand them in a way that is different from the way its designers intended them. This is an open implementation problem - there seems to be an answer, since the goals we humans have don't seem to be written instructions that we constantly re-interpret, but rather expressed in some other format. It is a technical problem that needs to be solved.

Objection 13: Couldn't AIs be built as pure advisors, so they wouldn't do anything themselves? That way, we wouldn't need to worry about Friendly AI.

Answer: The problem with this argument is the inherent slowness in all human activity - things are much more efficient if you can cut humans out of the loop, and the system can carry out decisions and formulate objectives on its own. Consider, for instance, two competing corporations (or nations), each with their own advisor AI that only carries out the missions it is given. Even if the advisor was the one collecting all the information for the humans (a dangerous situation in itself), the humans would have to spend time making the actual decisions of how to have the AI act in response to that information. If the competitor had turned over all the control to their own, independently acting AI, it could react much faster than the one that relied on the humans to give all the assignments. Therefore the temptation would be immense to build an AI that could act without human intervention.

Also, there are numerous people who would want an independently acting AI, for the simple reason that an AI built only to carry out goals given to it by humans could be used for vast harm - while an AI built to actually care for humanity could act in humanity's best interests, in a neutral and bias-free fashion. Therefore, in either case, the motivation to build independently-acting AIs is there, and the cheaper computing power becomes, the easier it will be for even small groups to build AIs.

It doesn't matter if an AI's Friendliness could trivially be guaranteed by giving it a piece of electronic cheese, if nobody cares about Friendliness enough to think about giving it some cheese, or if giving the cheese costs too much in terms of what you could achieve otherwise. Any procedures which rely on handicapping an AI enough to make it powerless also handicap it enough to severly restrict its usefulness to most potential funders. Eventually there will be somebody who chooses not to handicap their own AI, and then the guaranteed-to-be-harmless AI will end up dominated by the more powerful AI.

Objection 14: Machines will never be placed in positions of power.

Answer: There are cases where humans are currently kept in the loop where it might not be necessarily needed, but the primary reason for that seems to be a worry of special circumstances arising which the machines cannot handle by themselves. Still, as technology gets more reliable, those concerns are likely to diminish - and an AI capable of handling a /wider/ spectrum of situations than a human is exactly what you would want to replace most supervisor operations with. As computers become more human-like, humans will become less reluctant to give them power, quite likely even trusting them more than real humans.