There's a basic overview of the new stuff. Didn't look very hard though, so you could probably find a more comprehensive list in about 30 seconds with Google.
The big things for me are that it boots quite a bit faster on my aging laptop, and it works much better with Intel GMA integrated gpu's than Jaunty did. I think the minimum RAM requirement went up a bit, but I'm running it on a Pentium 4 laptop with 216megs and it works ok.
Personally I'm waiting for this OpenSUSE thing I've been hearing about to finish its closed beta. Its like a custom distribution builder, similar to Slax except you don't have to be a genius or a lifelong Linux user to figure it out.