I heard about this a few days ago, but it was just in a discussion thread and the person doing this didn’t have their website updated. Now they do. Ben Heckendorn has created the ultimate ultraportable: The Atari 800 XE Laptop. It has a full keyboard, full 2-player controls, 16MB of storage, an 8″ TFT Display, and runs off of a Ni-MH battery.
It’s based on an Atari XE GS (Game System), which came out in 1987 (the last Atari 800-type computer produced).