Apple Computer Inc., according to the online Music Store web site, are ready to unveil iTunes 4.5, which will contain numerous new features including iMix, music videos, video trailers and free weekly downloads.
The free weekly download is one single, which will only be available on Tuesdays. iMix allows the user to publicly show their own playlists which will help the user "boost your ratings and top the charts."
The new Video Music Section allows the user to watch the clip of 72 songs so far. iTunes 4.5 also allows Windows Media Files to be used, so long as they're unprotected files. Source