Just pointing out here what some of the media is saying.  Here's what Rick Klein said at ABC's Political Punch:

There's been lots of speculation this week about whether Sen. Barack Obama has an Iraq problem. He does now.

His comments Thursday, saying that he will "continue to refine" his plan to withdraw combat troops from Iraq inside of 16 months, seems likely to leave the campaign on the defensive on this issue for days or weeks.

http://blogs.abcnews.com/politicalpunch/ 2008/07/obamas-iraq-qua.html

The title of the piece?  "Obama's Iraq Quagmire"

To be fair, Iraq is going to be a no-win situation for whoever is there.  But though a strong Clinton fan, I always believed that the firm pull out date was the best approach, for a lot of reasons I won't go into here.  I think Obama should be sticking to the firm pullout date.