Apple recently announced at Macworld 2008 that they would start renting movies from ALL the major motion picture studios. With all the excitement many people forget that you can still buy movies on iTunes. Movies are for sale from Paramount, Lionsgate, MGM, as well as all the studios currently owned by Disney.
Paramount seems to have the largest library. All of these studios are also renting some of their features while just offering others for sale. Fox, Sony, and the other major studios have started to allow rentals through iTunes (requires version 7.6) and these movies will be viewable on the computer, ipod, iphone, and apple tv.
To access movie rentals open the iTunes store and go to the movie section. There will be a number of areas advertising movies for rent. Feel free to browse through the available movies by content categories or searching for a title that you hope is currently available. The library is continually being updated so you may have to wait to watch a certain movie on your new iPod Touch while riding public transportation into work.