The need for this news item arises because the BBC has a story with the headline "Microsoft shares source code for Kinect gadget". This isn't the case - Microsoft has open sourced some samples that use the Kinect.

The BBC is often taken to be the source of all truth and so it is important to correct it when it gets it wrong. The news item says

Before now anyone wanting to use the Kinect had to work via an official software toolkit that hid the underlying code.

You still have to use the SDK and it still hides its inner workings. What Microsoft has open sourced is a set of examples  These do help with the task of getting to know the SDK and how  get something working, but they most certainly add no new information over and above the SDK documentation.
Put another way - Microsoft hasn't released any information that wasn't already available and it hasn't placed the SDK or the Kinect Drivers into the category of open source.

More to the point, the samples were already in the 1.6 SDK so all that has happened is that they are easier to get at because they are uploaded to CodePlex.

If you want to work with the Kinect using open source then you still have to go back to the open source drivers created when the Kinect was first released or use the PrimeSense drivers via OpenNI.

Getting away from the BBC's sensational headline, it is worth adding that the samples are welcome and cover the usual areas -  using the Kinect video, depth camera, audio and extra API features such as fact tacking. It also has some more complete applications including Tic Tac Top and Gestures.The programs are available in C#, C++ and VB and make use of WPF and DirectX.  Some of the samples were already in SDK 1 and they are all in the 1.6 release. 

So basically the news is that Microsoft has uploaded some Kinect sample programs to a website and made their status as open source clearer than the SDK did. This isn't a huge step for Microsoft nor for the Kinect.

What is interesting, and what this episode does draw attention to, is what Microsoft hangs on to that is of importance. Clearly the drivers are irrelevant because there are two alternative open source drivers and the Kinect hardware is made by PrimeSense so its not proprietary in any real sense. Any company could put together a depth camera like the Kinect using PrimeSense hardware. They could also put together a reasonable SDK that matched the Kinect in all but one feature - body tracking. The Kinect still has the state-of-the art AI based body and soon hand tracking software. If Microsoft was to make this available as open source then it would be a cause for a sensational headline.