Cyborgification.
Cyborgification and nanomachines.
That's cheating. The whole point of AI is that the machine can "think" for itself.
Having no idea how intelligence arises or its intrinsic characteristics makes aiming for it sort of like trying to shoot the purple barglesnorfer without knowing what one is or looks like.
This is a very key point. If we're waiting for some esoteric definition of AI, like "Terminator 2" wherein the machine "learns the value of love", we may be waiting forever. Most emotion is chemical anyway; completely separate system.
However, going the other way, if we want to define AI as simply passing the Turing Test, well, I'd argue
Cleverbot is already there (but that's probably only due to the terrible quality of most web chat in general). In other words, we can build a machine that can fool people into believing that it is intelligent, but what does that really accomplish?
It is also important to note the vast amount of technical analysis that has been automated via software in the past 20 years. Now, many argue that "rules" based systems are not "true" AI (as compared to an Adaptive Algorithm), but for a pragmatist, this is good enough. Example: I just coded a system to ban users after detecting a certain amount of forbidden activity; in practice all I did was implement a standing company procedure. That's not "real" AI to a researcher, but to a business owner, who can now reduce payroll because that function is successfully automated, its better.
But to get to the core of AI, I agree with most in this thread that adaptive/evolutionary algorithms are the best shot we've got (just run a zillion iterations of trial-and-error and hope for the best). Of course, "intelligence" is a fickle mistress indeed. I am reminded of this relevant anecdote:
The US ARMY was interested in developing an AI system to identify whether or not tanks were present in given recon photographs. An adaptive algorithm was created, and the AI was shown a thousand photos- some with tanks, some without. After some tweaking, the AI began working with an astounding success- 90+% accuracy. The researchers upped the ante, and showed the AI pictures where the tanks were covered by trees and other obstacles. After X iterations, the AI was succeeding again- 90+% accuracy. The researchers patted each other on the back, proud of their unparalleled success.
Sadly, it was eventually discovered that half of the photos- those with tanks- had been taken in the early evening; those without tanks had been taken in the day. All the AI had learned to do was identify the level of daylight.
A substantial blow to intelligence- both artificial and the real thing.