I hate to break up the presidential water cooler (well, not really), but the music business has interesting news today: Amazon will sell music free of digital rights management (DRM) software. Apple already announced earlier this year it would do the same. Both companies have only signed with music label EMI so far, but another entrant to the market means one thing: finally, an emerging marketplace in digital music sales. DRM meant iPod users could only buy from Apple, Zune users could only buy from Microsoft’s store, etc. Now, the stores will actually compete against each other, which should mean lower prices.