I think that's a great idea.
Joe has already been doing tons of international diplomacy trips. Hillary has already said that she's not likely to be secretary of state for a second term, so it would be a way to retain Hillary.
But I totally disagree with the notion that Hillary would be chosen as an antidote to Sarah Palin for 2012. This country would NOT elect Palin. Everybody knows that. It's only the media that has given Palin wings. If Palin won the republican nomination, then it would be a shoo-in for Obama.