I enjoyed this post by P.M. Carpenter on Hillary's prospects:
There is nothing left but strained, over-the-top shenanigans in the service of pulling off a mathematically impossible fantasy.
That, or a polite, reasoned withdrawal in the interest of faits accomplis and party unity, leaving her, in eight years, still nearly four years younger than the current Republican nominee.[...]
She can now stay mired in the silliness and do the party a whole lot of damage, or she can crawl out of it and do the party and herself a whole lot of good.
She can, that is, simply withdraw now. The test of Wisconsin was whether Obama would continue taking occupation of virtually every demographic territory once so confidently held by Mrs. Clinton. He did, and he did it decisively.
I think Clinton could still come back, but it would require a massive change in fortune. Expect the next two weeks of campaigning (and the debate this week) to get ugly. Clinton will keep coming after Obama, trying to find a line of attack that works. The person who is most likely to benefit from that strategy: John McCain. McCain gets to see how going negative on Obama is likely to play with the electorate without having to invest his own money or risk tarnishing his image.