Here's a project I posted last night...it's an 81 LED RGB coffee table (that you've probably seen a while ago) but with my new Bluetooth shield added. It's pulling data from Twitter and will let you tweet your own pixels and view the results live on Ustream. And of course I can see the results live in my living room.
So far we have some pixels in corners, someone wrote "Hi", what can you draw?
Lots of photos, diagrams, and code here: http://macetech.com/blog/node/93