The update is around 90 MB and fixes the following "issues" – hit your software update or visit here to get it.
* Resolves issues browsing the iTunes Store.
* Addresses a performance issue where iTunes may become unresponsive.
* Fixes a problem where iTunes may unexpectedly quit.
* Fixes a problem syncing Podcasts in playlists to iPod or iPhone.
* Fixes a problem sorting albums with multiple discs.
* Addresses an issue with the Zoom button not switching to Mini Player.
* Improves application syncing for iPod touch and iPhone.
* Genius is now automatically updated to show Genius Mixes.