The OLPC project has just launched OLPC USA: XO-1 laptop sales at $400 per computer in a “Give 1 Get 1″ program:

Starting November 12, One Laptop Per Child will be offering a Give 1 Get 1 Program for a brief window of time. For $399, you will be purchasing two XO laptops - one that will be sent to empower a child to learn in a developing nation, and one that will be sent to your child at home. The devices will reportedly ship before the late December holidays.

via OLPC News