I'm also skeptical. As I recall the GPL only requires source code to be made available to someone who has been provided the binary; ie in effect MS would only

I'm also skeptical. As I recall the GPL only requires source code to be made available to someone who has been provided the binary; ie in effect MS would only have to make source available to their customers if asked, there would be no requirement to make it available to the community at large. Last time I checked, e.g., Windriver was only making available their linux patches to customers who had purchased their embedded linux flavor, citing precisely this interpretation.