Sadly, no solution is available for the psets. Personally, I don't see any value of assignments on the web without solutions as you cannot be sure of your answers.
on the other hand, many of the problems in CS 229 are proofs and derivations that are very similar to those in the lecture notes (forcing you to understand the lecture notes in detail). as such, they can't just "tweak the problems every year" like you'd do in a lower-division math course - they're more like the exercises in an upper division math text (some problems are in fact referenced in the notes).
so, it is perhaps understandable why they might not want solutions floating around the internet forever.
(yes, i know that the stanford honor code is supposed to deal with this.)