I'm still going to cast my vote for Wes Clark today, even though he's no longer officially running. Screw it... I figure I put in all that time, I might as well get some satisfaction.
In November, I'll pull the lever for Kerry, even though it's hard to get too excited about it. The closest correlation I can come up with is the 1996 race. Clinton was still very popular with his base (as is GW Bush) while Dole did very little to excite anyone. People were motivated to vote for him simply because they didn't like Clinton.
A lot of people will pull the lever for Kerry for the same reason. I don't see people getting very excited about him, but they figure anyone is better than Bush. So far, Kerry has shown a strong inclination to fight back when attacked. Believe me, he's going to need it.