Not long after iTunes 8.1 itself was released, Apple has gone and sent out version 8.1.1 for your updating pleasure. Don't get too excited; this isn't bringing any huge new features, as indicated by the version number, but there's still some nice stuff in there.
What's the biggest improvement in iTunes 8.1.1? The ability to rent HD movies via the iTunes Store. Neowin originally reported this a while back, but it seems it's only become available now.
Here are the official release notes from Apple themselves:
iTunes 8.1 is now faster and more responsive. You will enjoy noticeable improvements when working with large libraries, browsing the iTunes Store, preparing to sync with iPod or iPhone, and optimizing photos for syncing.
In addition, iTunes 8.1 provides many other improvements and bug fixes, including:
Supports syncing with iPod shuffle (3rd generation)
Allows friends to request songs for iTunes DJ
Adds Genius sidebar for your Movies and TV Shows
Improves performance when downloading iTunes Plus songs
Provides AutoFill for manually managed iPods
Allows CDs to be imported at the same sound quality as iTunes Plus
Includes many accessibility improvements
Allows iTunes U and the iTunes Store to be disabled separately using Parental Controls
iTunes 8.1.1 adds support for renting HD movies and provides a number of bug fixes, including addressing issues with VoiceOver and syncing with iPhone or iPod touch.
So please, iTunes users, head away to the program and hit 'Check for Updates', or, of course, visit the iTunes page itself.