iTunes 10.6 Released
iTunes 10.6 has been released alongside iOS 5.1. The update includes 1080P support for movies and TV shows downloaded from iTunes Store, but otherwise is fairly minor and includes several bug fixes and improves song matching and how album art is handled.
You can grab the 10.6 update directly from Apple at the link below, through Software Update, or through iTunes itself.
If you intend on performing a manual iOS 5.1 installation through firmware, you’ll want to download iTunes 10.6 beforehand as well.