After upgrading my trusty iPhone4 to the new iOS5 software/firmware, I discovered that I could not access the itunes store from phone to download updates for my apps.
I did a lot of searching, with no real answers until I stumbled on a suggestion to fire up itunes on my computer, click on Store > View My Account, login with your Apple storeid and password, and then select to deauthorize all computers.
Yes — deauthorize all computers. In fact there’s a little button that lets you do it very easily. I did so with fear and trepidation, but the result was that it immediately worked. I was able to access the itunes store from my iphone and download the available updates to my apps.