For the last six days, app updates have not been showing up in iTunes on the Mac and on the PC for many people around the globe. I can confirm that app updates have stopped appearing in iTunes on my Mac (while those missing updates still appear in the App Stores on my iPhone and iPad). The problem seems to have started last Tuesday. Since then, no updates have appeared in iTunes.
Not all of us as TUAW are experiencing the loss of functionality of app update in iTunes, but there is currently a thread in Apple's discussion forums with over 120 replies of people stating that app updates have stopped appearing in iTunes on both Macs and PCs. It's not clear why those affected are and others are not. Reports of missing updates are coming in
