This is pure speculation, but I'm guessing more endorsements tomorrow for Obama, since he is doing no campaigning anywhere tomorrow. Feel free to mark my diary as spam, haha.
It's just a guess, but no campaigning has lead to some other big endorsements before. My guess is that he is heading out to Chicago for maybe a day or two, and spend some time at his headquarters and house. But, i doubt he would leave the entire day to Clinton, so thats my guess. Both the NYTimes and a source over at The Hill are saying that at least 20 endorsements over the next 2 weeks are expected for Obama, a minimum of one for each day. Who could it be? A Senator, Governor, mayor party official or a bunch of "small" SD's at the same time. What ever.
If it's a BIG (a la Richardson, Kerry, Kennedy, Dodd, others) endorsement, then we will most likely see it in a few minutes or an hour popping up from the AP or other sources, they usually give a notice before.