I'm another Tmo Nexus S owner who had manually installed ICS 4.0.3 when it was first available back in December 2011. Two days ago (Mon Apr 2 2012) I got an automatic update to ICS 4.0.4. Yesterday I saw that Google+ was the biggest battery user & since I don't use it I disabled it, because I wasn't allowed to uninstall it.
Since disabling Google+ I've been surprised that the built-in Gallery application is the largest drain reported by on my Battery status page. This morning the phone has been unplugged for about 2.5hrs, and Gallery is at 69%. Next is Wifi at 7%, Cell standby at 6%, Screen at 6%, then Android System, Phone, and Android OS all at 3% each.
I never use the Gallery since I prefer QuickPic. But I can't disable or uninstall Gallery, and if I Force Stop it I'll still see it running when I check a few minutes later. I checked my three Gmail accounts under Gallery Settings and none of them are set to sync - Sync is OFF for all three Gmail accounts in Gallery.
Since it's the most obvious explanation, I'm guessing that disable Google+ has caused a problem with Gallery, but my battery drain will be bad again if I re-enable Google+. Anyone else seeing this sort of thing with ICS 4.0.4?