Of course I'm evil. I'm writing Ajax in .Net.... Sorry, have to because of our code base, until we re-write it from scratch....
Ruby is interesting but its also idiocyncratic and its a dangerous UI/API lock-in at this point. If I had my choice I'd prolly follow alex and write python with jython (am I kidding? you decide!

) to make the raw AJAX calls... Still lookin for more resources, hopefully several abstractions lower than Ruby...
Cheers,
Buffy