Oh, I don't know: Obama/Edwards makes some sense from a political POV, if not necessarily from a policy one. Edwards is well-understood to be much more populist than Obama -- he's the one Democrat who campaigned on a distinctly left platform, whereas Clinton is focusing on centrism and Obama is mainly trying to stay away from the left/right scale altogether. So Edwards might shore up the left side of the Democrats if that were desired. (Although it could also scare off some Republicans, so there is a potentially serious cost there.)

And he's a southerner, which doesn't hurt. Between that and general dissatisfaction with the Republicans, it might put some of the South into play -- and if the Democrats take any significant fraction of the Deep South, this could go from being a win to a wipeout.

So I think it's possible. Whether it's *likely*, I have no idea -- most importantly, I have no clue how the two feel about each other or what the chemistry would be like, and that matters a lot...