Is it common knowledge that John Edwards, as the NYT puts it:
concluded that Mr. Kerry lacked fight for not filing a legal challenge to the  election results.
I doubt any Democratic candidate really wants to get into the question of a 2004 recount. But if Edwards really believed this, it'd be pretty interesting to hear him--and the other candidates--talk about it in a future debate. If people really believe the last election was illegitimate, that's not something to be swept under the rug.
P.S. This Times story about the '04 Edwards-Kerry relationship also says (in tension with the point above) the Kerry camp was frustrated that Edwards didn't play more of an attack-dog role after he joined the ticket. The Gore people said the same thing about Lieberman! Memo to the '04 Democratic nominee: Pick a running mate who doesn't give a damn about being like a nice guy....