I want to phone a friend! No, wait, 24-70mm f/2.8L, final answer.
Seriously though, unless you shoot a lot at 35 or 50, a zoom at f2.8 has much more utility than a prime.
One note from our good friends at lens rentals on the 50mm:
"Well, we could talk about this for hours, this is one of the most controversial, irritating, and spectacular lenses in the lineup." -- it has a learning curve
That said, my only real complaint (and it's probably because I've heard other people say it so much that I noticed it) that the much more affordable 50mm f1.4 is a bit slow on the autofocus (not kit lens slow, but you get the picture).
Re: Is it dumb to buy a new version when a new one is coming out?
1) A new one will either be released tomorrow . . . or a new one won't be released for 3 more years
2) SOMETHING may be coming with a new DSLR . . .
3) A new DSLR will either be released this month . . . or A new DSLR will be released in the next 18 months
All of the above is as true as anyone randomly posting on twitter, so you can take the advice everyone doles out daily here:
Buy it if you need it, wait if you want it . . . or anything in between.
I'm considering picking one up and seeing how there's a direct correlation of the peace in my household to lenses purchased (directly inverse that is) I figure I'll wait another month and see if anything turns up.