Petey pointed out that the latest CNN poll (PDF) shows some very clear patterns in the head-to-head presidential matchups. In particular, John Edwards polls as the strongest Democratic candidates whereas John McCain polls as the strongest Republican.
Of course, it's hard to know what to make of this sort of polling (except that as a white man, I'm patting myself on the back) since the events of the campaign really do change things. How much does Edwards' relative cash shortfall matter as an electability issue? And I bet most of the respondents to this poll don't know (yet) about Rudy Giuliani's criminal associates -- a series of charges that's probably more damaging than any muck that'll ever get dredged up on Romney. But despite the uncertainty, I think you do need to count this as a serious point in Edwards' favor when you combine it with the considerable merits of the policy positions he's staked out. Meanwhile, for the GOP I think nominating McCain is clearly the right across a whole variety of considerations, but I guess if you really, really, really hate immigrants it doesn't look that way.