Looking ahead for the Dems:
PA: 188 delegates
Total of 712 delegates still to be chosen. If Obama and Clinton split these, this'll give Obama 1411 + 356 = 1767 pledged delegates. With 207 superdelegates already stating they will support Obama, that gives him 1974 altogether--only 51 short of the nomination. A switch of 26 delegates from Clinton's side and he's got the nomination. Or, even fewer, and the settling of some caucus states (like Iowa) result in more delegates pledging to Obama as they go through their process.
Obviously this is all subject to change. Clinton seems very strong here in PA, but we have some weeks to go. However, what gains Clinton makes in PA are likely to be overturned in Indiana and North Carolina where Obama has healthy leads himself.
On the Clinton side, there really is no way she can win it with Florida out of the picture and Michigan less and less likely. She's trying to take super delegates but the numbers just aren't there for her. Splitting delegates in the next 11 contests (not easy to do) will give her 1598 pledged delegates. With 237 super delegates this leaves her short 190 delegates.
There are 356 super delegates (796 total - 211 - 237) who have not endorsed a candidate. Clinton *might* be able to pull it off by somehow convincing a majority of the uncommitted super delegates to support her (despite Obama's leads in the popular vote, pledged delegates, and states won). I have no doubt they will do what they have to do. But the numbers are against her.