Seems like a legit source to me.
So Microsoft has been updating all of their Windows 8 applications in preparation for windows blue and they updated the main Games application.
It previously looked like this
now it looks like this
Doesn't Look like Microsoft will be doing anything big publicly at GDC even though they have the usually Xbox space. The event they had at last year's GDC was press only and embargoed till after GDC iirc so anything could still happen. I personally think showing that not showing the nextbox at GDC is a bad move as your going to see Sony in a lot of the headlines for the next few days.
On that note I think I've found why Microsoft wpn't be showing anything until probably Late apirl-E3. They announced today that Build 2013 will be taking place in June.
http://www.buildwindows.com/Now it makes sense that Microsoft would want to hold off for showing the xbox. They will have a small event before E3 followed by a bigger E3 showing for the consumer. Than at Build they show off and have workshops about all of the developer aimed stuff the regular consumer doesn't care about. This will allow them to show the further expansion of thee one code base making stuff for all three platforms.
[imghttp://cdn.wpcentral.com/sites/wpcentral.com/files/styles/large/public/field/image/2013/03/devices.PNG
I liked what I watched of last year's build but hot damn if those aren't expensive tickets. I really don't understand why the tickets for Build and Apple's WWDC are so freaking expensive. I mean even counting the free swag going to Google I/o is only $900 and has a student option for $300.