I could definitely see Al Gore going for VP again, if he ran with Obama.
First, he might calculate that's the best way to win.
Second, they would present it as though they were "co-Presidents"---hey, it worked for the Toons. They'd say they have Obama "fresh, young, new-to-Washington perspective" and Gore's experience in the White House, blah blah blah.
Third, if it takes being VP again to finally strike a personal blow against the Toons (and you gotta believe Algore harbors some mighty fine resentment against those two for Bubba's ridiculous conduct which, um, *complicated* Al's best chance at winning the presidency in 2000), he might just do it.
Fourth, Al Gore can claim that one of his most cherished causes in global warming and that, in the role of VP, he would have more flexability to continue his "important" work in that area, all the while President Obama could benefit from his "experience."