The OLPC (One Laptop Per Child) Project has releases Human Interface Guidelines for the machine.
This is a great piece of thinking and is, aongst other things, the first really good application of Fitts Law that I've seen.
I was going to write some stuff up about it, but Mikes Journal has done a great job already.
If you're into Interaction Design, you might want to follow Nadeem's occasional ramblings too.
As he says, we are currently looking for talent in this area.