My nexus s has been operating brilliantly up until a few days ago. Suddenly I am unable to get any sound from the rear speaker, although everything else is working as normal.
(one exception - my Google music app seemed to be operating oddly - not working, and not updating (with some error message like 'can't find file'), but this was for a long time. That issue disappeared recently when i updated to Google music beta, which worked for a few days).

I had a brief discussion on this thread also: