Is a Clinton-Obama/ Obama-Clinton ticket feasible?

I ask this question seriously: Is a Clinton-Obama ticket (or Obama-Clinton ticket) possible? feasible? desirable? Come the convention, will the primary season wounds inflicted be too deep to overcome?

From my quite isolated vantage point across the Atlantic, I see two strong candidates who together appeal to an astonishingly broad demographic, and I am hardly alone in hoping for unity (and the earlier the better).  

I also see the Republicans in the wings sharpening their racist, sexist, and "compassionately conservative" knives.

A Clinton-Obama//Obama-Clinton ticket?

[Disclosure: I ask this as an Edwards Democrat (I support his populist, anticorporate platform, and hope that the two main contenders will pay much more attention to the poor and disenfranchised of our nation).]

Would Hillary be willing to settle for Veep? Would Barack? Could either put aside her/his presidential aspirations for the sake of an unbeatably strong ticket?

Would such a ticket be a better defense against the inevitable Republican slime machine, or would it just give these unAmerican types a bigger target?  What seems certain to me is that they are going to go full-out to play to the ugliest fears and most fetid cesspools of the American psyche to try to inflict as much damage as they can.

Is there any way to minimize the primary-season bloodletting such that these two could be on the same ticket? Or would it be better to bring in someone else (Edwards?) as veep, regardless of who is nominated?

Is there anything that we can do now to ensure that the strongest ticket will remain possible despite the continuing contest for the nomination?