iTunes Plus, the new "standard" for Apple's iTunes store, uses 56-Kbps AAC encoding but it's DRM free. That means there are no limits to how many times you can "burn" copies, and it means that the file will play on a lot more devices, including Mac and Windows computers, and many more portable digital music players than iPods.
In early January, Apple announced that they were switching to iTunes Plus, and that you could "upgrade" previously purchased songs for a fee (30 cents a song, 60 cents a video, 30% of the price for most albums). The problem was that you had to upgrade 'em all in one fell swoop—which could be pretty pricey for lots of us. Plus, there are songs that, to me, just weren't worth it.