Good news! It looks like Onskreen is making Cornerstone open source.
If you currently have a Xoom they have an official ROM for you to try. I'd like to hear about folks experience. For other devices they provide the source but you have to incorporate it into a ROM. I'd love to see how this works on a Galaxy Note, Nook Tablet, WHATEVER!

Check the link in post #1
http://www.onskreen.com/cornerstone/