via crunchbase: AppJet intends to simplify the process of writing web applications. The applications are programmed on a web based text editor in the simple but powerful JavaScript programming language. JavaScript is used on both the server and client side.
I guess they ended up realizing that the code editor was a better product/market to go after than the app creation/hosting itself.
Also, interesting that pg invested in the angel round as well, post-YC.