OMG Microsoft, budding developers WANT to write software that uses your technology. Not a great business move taking this long to release a SDK for PC. And what the hell is that 'non-commercial' crap about?
The non-commercial stuff is about Microsoft wanting to be sure that if someone *does* come up with a killer commercial app, that Microsoft can charge them licensing and get a piece of the pie that a few months ago they said they didn't want...
Wasn't there an article talking about how stupid and pointless interfacing the Kinect with a PC is just a month or two ago? Not that I agree whatsoever, just find it kind of funny that that kind of article gets posted, and then MS announces and SDK.
This was the best they could do, after being framed by Johnny Lee (one of the developers of the Kinect) there as no need to keep it xbox only, you should check out http://www.kinecthacks.nl to see a lot of cool stuff and videos of the hacked kinect for the pc, awesome.