RIM's got an application that brings iTunes and BlackBerry together. Called BlackBerry Media Sync, the software lets you ransfer entire playlists or specific song files to your smartphone. Also, changes to your iTunes playlists are automatically updated on your BlackBerry when you sync with your PC. The only caveat is the musc files must be DRM (digital rights management)-free for listening on your BlackBerry. RIM's posted a flash demo covering BlackBerry media Sync's features
here. You can download the application
here.