The American electorate is now basically split into thirds, and how Hillary proceeds from here will shape the future of all three groups.

If Hillary sits out the general election season, or campaigns halfheartedly for Obama, and McCain wins, she becomes the automatic frontrunner for the Democratic ticket in 2012.

Hillary of course must be aware of this calculus and as such is faced with an unprecedented moral/ethical choice heading into the fall. If she campaigns hard for Obama, and helps pull all of her disaffected voters back onto the Democratic ticket, Obama will probably win this thing in a landslide. If she pulls a slowdown, however, and a big chunk of her voters sit this one out or vote for McCain, it will greatly enhance her own prospects for the presidency four years later.