So this just started happening to me 2 weeks ago. I will get on my iPhone and be checking out the app store, or I will see that I have updates when the number appears on the badge. After installing one update I go back to get another and there are often anywhere from 1-20 app updates now. The problem is, they are all for apps that don't actually have updates and the ones that actually have updates are gone. Sometimes it is even saying that the version I should "update" too is a version I know is one I got weeks ago. (one case in particular is Hero of Sparta, currently v1.0.1 comes up constantly saying to update to v1.0 according to the app store.)
I can see no pattern to this madness or way to always get it fixed. Sometimes just closing and reopening the app store works, sometimes it doesn't. Sometimes resetting my iPhone works and sometimes not. The only thing for sure is that I never get false updates when looking for updates via iTunes on my computer. Only on the iPhone.
Has anyone else had this happen? Just right now I was flipping to my game screen and saw I had 3 updates according to the app store, iTunes confirmed this. After downloading one of them I went back and now it says I have 14 updates, none are for the other 2 apps I need to update.
Edit - Also note, when I select one of these so called "updates" it does say that it's already installed and won't let me actually download it.
Edit 2 - Ok, now iTunes (on my computer) says I have 29 updates! I really do not know what is going on here, they are all old updates. One is for AIM 1.4.1 and I know 2.0 came out last week.