The original poster was right, this was very easy before itunes 11. There are many occasions when a normal person might not want to play all songs on an album, and it does seem like a really basic function for a music player. And sriramfromhyderabad correctly noted the easiest workaround is to right-click (if you have right-click enabled at all).
Perhaps it would detract from the minimalist presentation that Apple apparenty seeks, but it would be extremely convenient and functional if you could uncheck songs in the new Album View. This is a case where I myself would prefer function over style.
The rumor is that Apple doesn't monitor these forums (which I doubt), yet there may be a chance that if enough users ask for it through their (stated) feedback channel, we could get a fix to something that was not broken.
http://www.apple.com/feedback/itunesapp.html