I'm going with Kinect related development. The system would have been under heavy development 3 months ago considering that the system isn't going to be released until over a month after this last financial report. I don't know how many months out they start production, but at my company we work on the devices straight into the first production run (we aren't production oriented though).
Also, R&D could be up due to Kinect system software. From APIs for developers or trying new techniques. It was revealed not to long ago that they changed the software to use the neck as the anchor point of the body. They could be improving motion tracking, voice recognition, and a whole host of software related features.
Either way, not to interesting until semi-legitimate rumors start spreading about some new item from Microsoft.
