I am amazed that this fact hasn't been discussed more: After Obama's win tonight, the delegates gained for Hillary on March 4 have now been equalized.
After the "Potomac" primaries, the Clinton camp pointed to Texas and Ohio where they would catch up. The press agreed, making Texas and Ohio the critical place for Hillary to take a stand. She won a handful of delegates, which Obama has now evened out after wins in Wyoming and Mississippi.
If the press starts to focus again on delegates, Hillary may not make it to Pennsylvania. If they keep allowing her to define the race, I guess there's a chance for her. But at this point, there is simply no way she will win the pledged delegate count. And if it was anybody - ANYBODY - other than Hillary, she would be getting tremendous pressure to concede the race for the good of the party.