When we last visited Wal-Mart's attempt at DRM-free music, they had only managed to get EMI and Universal Music Group signed up for the DRM-free portion of their store. They've now decided to go all-MP3, but they're still stuck without Warner Music Group and Sony BMG, which are unfortunately the top two record labels.
As Wal-Mart switches to the MP3 music format and redesigns its music store, it leaves behind Microsoft's digital rights management technology, which prevented the songs it sold from being played on iPods. The company has also ditched Sony/BMG and Warner Music Group, for now anyway, probably due to licensing squabbles about the terms of the transition to unprotected music.
Most likely, this is a temporary situation that will be resolved by additional mingling by bean counters at both companies, but one wonders whether Wal-Mart and its customers would have been better served by waiting until all of its ducks were in a row and then announcing a comprehensive DRM-free store on the level of Amazon MP3.
True, it would make more sense if Wal-Mart had not just all the labels signed, but Mac and Linux support as well. Oh, and don't even think about using a non-IE browser on their new site. That's just one more problem.