There's one good reason neither Barama nor Clinton will accept the VP post under the other.

IF the Democrats win the White House in November (probable, but still not a sure thing)...

The resulting Presidency will be either a good one or a bad one.

If it's a good one, the President will run for a second term.
If it's a bad one, the public will probably not vote for a another Democrat, especially one associated with a failed administration.

If a Democratic President completes a second term, even if successful, the country will probably be in a mood for a change in parties anyway. An 8-year VP does not necessarily make for an exciting candidate, or give a politician much chance to do anything except play second banana for almost a decade. If the President's second term is perceived as a failure, his VP doesn't have a chance.

I don't think either Clinton or Obama will be willing to sacrifice their political careers for 8, or even 4 years for a long shot at winning. Having said that, it does make more sense for Obama to accept VP than Clinton, at least he can pick up some experience that way. But that didn't help Al Gore much, did it?

On the Republican side, it makes a lot more sense for Huckabee to accept VP. McCain might succumb to that temptation to unite his party, and (because of McCain's age) Huckabee has a fighting chance to replace a deceased or ailing McCain, perhaps even in the first term. Huckabee will fade into obscurity after the election, he has to make his move now. I also suspect that if McCain has a very successful first term, he still might decide to retire at the end of it. He doesn't strike me as the kind of guy who is so consumed by personal ambition that he can't just quit while he's ahead and enjoy the rest of his life.

I stilll think that McCains's best running mate will be a prominent black or woman, or both. Colin Powell or Condoleeeeeeeeeeeza! What better way to steal the wind from the Democrat's sails? Again, you heard it here first, folks.