I've added a new element to the blog. Note the fancy superdelegate counter in the top right corner. (Thanks to the Superdelegate Transparency Project for the nifty widget!)
The clearest indicator of the Democratic primary's outcome is this: if Obama gets more than half of the superdelegates in his pocket, it's over.
There are 794 supes, and half of that would be 397. Obama currently has 221 superdelegates in his pocket. So all he has to do is convince another 176 superdelegates to commit to him, and that's the ball game.
Clearly Clinton can't catch up in pledged delegates in any realistic way, and so she's staking her dwindling hopes on superdelegates. (Well, all right, she also seems to think that pledged delegates are going to flop over to her side, but I don't see that happening in the real world.) So the way to end it is to get commitments from enough remaining superdelegates to clinch the nomination.
Obama appears to have gained nine superdelegates in April alone, after picking up around 2 dozen in March. The supes are going to start declaring with more speed as the voting draws to a close, and this thing will wrap itself up neatly.
Eventually, I feel certain the conclusion of the primary race will become apparent to all participants.