From what I saw of the game, it was just another dogged defensive display from another relegation-threatened team, and we didn't produce enough to deserve the win. End of.
Rather unfortunate from our point of view that Vidic wasn't (as he should have been) sent off for United - if not for the first challenge then for the even more unnecessary one in the second half. And anyone who says he shouldn't have been should take a long hard look at what Koscielny was sent off for against Newcastle at the Emirates.
A stupid result, but we are still by no means out of it.