Daniel Bigham has released another one of his popular sync apps for the BlackBerry PlayBook. His latest is a sister app for his iTunes Sync app called iTunes Upload. What it does is upload the music you have purchased on your PlayBook from 7Digital to your PC running iTunes. Currently it only supports Windows PCs unlike the iTunes Sync app which supports both Windows & Mac. You also have to have a little app running on your PC (same app as iTunes Sync) to enable the transfer.
If syncing your music purchases back to iTunes is something you have been struggling with check out iTunes Upload for $1.99 in App World. Kudos to kiddo2050 (different Daniel) for pointing it out in the forums.