Josh Green makes the case, with an interesting reportorial tidbit: "Obama and Gore have been speaking regularly, about every two weeks or so."
Josh offers a list of reasons why Gore might choose Obama. I'll add a key point obvious to insiders but perhaps not to everyone: There is no love lost between Gore and Hillary. I very much doubt they're talking every couple of weeks. (I have heard that Gore and Edwards spoke a few times, by the way.)
But wait! What if Hillary gets elected? Does Gore really want to be persona non grata at a Clinton White House just as Washington finally tackles global warming? The more I think about it the more I doubt it...
P.S. MoveOn for Obama--overwhelmingly. The Netroots is finally starting to coalesce.
Update: Gore reportedly has no endorsement plans "in the near term."