Derek Slater wrote a nice post castigating Sony for pushing yet another incompatible DRM format into the market for music (Sony to Continue Self-Defeating Music Strategy):

And be ready for Sony to move to the domestic market soon enough, bringing more incompatability fun with it. I thought Sony was working with Phillips on DRM that anyone could license - a Phillips executive even said: "The electronics industry recognizes that Microsoft is a formidable player, but consumer electronics makers do not want to become dependent on Microsoft. They need an interoperable and independent system, DRM is an accelerator which will boost digital sales of media, because it will convince media companies their content is protected. It should not be a competitive weapon." Sony doesn't seem to actually buy that. They're trying to set the standard, and they want control over the devices.