"Acrylic" (code name) is the professional design program that brings together the richness of pixel-based painting and the performance of editable vector graphics for a more fluid and flexible creative workflow. Create sophisticated designs and graphic elements for your on-screen, Web, and print projects. (MSFT's Overview of Acrylic)
You can get more info about it here and dowload it here (good luck I am still trying).
I definitely don't see this as a Photoshop or Illustrator killer, more just an app that devies will dork with when they need a graphic and don't call upon a designer. Since Photoshop is in its billionth version, it is leaps and bounds ahead of this app so I am not likely to switch. But if it can get devies to stop saying things like “I did an image in Paint”, the world will be a happier place.
Oh, and I am glad this is a code name cause it takes too much mental power to spell Acrylic.