This is interesting -- Politico is reporting that one of the names floated by the people leading Barack Obama's search for a running mate is Ann Veneman. The surprising thing about that? Veneman is a Republican, and she served in George W. Bush's cabinet, as Secretary of Agriculture, during his first term.
"The search committee, now led by Caroline Kennedy and Eric Holder, raised Veneman's name -- among others -- in discussions with members of Congress, two Democrats familiar with the conversations said," Politico reports. "The mention of Veneman's name surprised Democratic lawmakers. The low-profile Republican was close to food and agriculture industries but clashed with farm-state Democrats and environmentalists during her tenure, which lasted from 2001 to 2004... Veneman's is one of about a dozen names suggested by vetters in a round of meetings with members of the House and Senate within the last few weeks."
Even given the political advantages to the pick, like the non-partisan message it would send and the appeal it might have for independents and women, it's still sort of hard to see this happening, given the Bush administration's unpopularity and what would almost certainly be a lot of displeasure on the Democratic side of things.