Oct 12
If you installed a beta version of iTunes along with the beta releases of the iOS 5 SDK, you may encounter a problem when trying to update to the public release version.
When I tried to update my non-development iOS device to iOS 5 with a beta version of iTunes 10.5 I was informed that I needed iTunes 10.5 to do this. Fine. Since I knew that 10.5 had been released to the public, I selected Check for Updates to download it. But the Software Update application said that there was no update available for me.
Solution: Download the iTunes disk image file here and install it.