Looks like JHymn is not able to strip the DRM off of any music or video purchased through iTunes 6.0, and that the new videos purchasable from the iTunes Music Store can only be played using iTunes 6. (Also note that you can’t easily revert to iTunes 5 after upgrading to iTunes 6.) Music that has already had the DRM stripped by JHymn will still play in iTunes 6.
It could be a bit of a wait before they reverse-engineer the new iTunes protocol. and until then I think I’ll pass on making purchases from their music store. If I’m going to give my hard-earned money for music, it’ll be a form where I can play it where I want, loan it to a friend or sell it to a used record store when I’m tired of it. The iTunes Music Store is great for convenience, but it’s short-term convenience in exchange for long-term pain.