This article provides two different solutions. To summarize for those not wanting to read the whole thing:
1. Connect the iPod to the computer you use to put music on it, and it should be unlocked after being synced. If that doesn't work:
2. Use the iPod Updater to restore the iPod to factory defaults. Yes, this will erase all your music and anything else on the iPod...but hey, it won't be locked anymore, will it?
