Not really. If you claim that a) intelligence is useful, and b) a maximally intelligent being that you have invented is useless ... you made a mistake somewhere.
And their work is just the formalization of Solomonoff induction -- the difficulty is in the derivation. People knew in advance that you can find the shortest theory to fit the data by taking a language, and then iterating up from the shortest expressible program until you find one that matches the data -- it's just that it's not computable, which for now, means useless, and the exponential approximation isn't much better.
Can you identify any working, useful system based on AIXI?
I don't think you have a reference for b).
Solomonoff induction is concerned with sequence prediction - not decision theory. It is not a trivial extra step.
The Open Thread posted at the beginning of the month has gotten really, really big, so I've gone ahead and made another one. Post your new discussions here!
This thread is for the discussion of Less Wrong topics that have not appeared in recent posts. If a discussion gets unwieldy, celebrate by turning it into a top-level post.