Gateway is still around as far as I can tell. They are not the best computers in the world and I do not think they are nearly popular, or powerful, enough to get in on a venture as risky as this one. I do not mean risky in a bad way because I believe Chromebooks will be a success.
Actually, they are still around (Gateway Official Site: Notebooks, Laptops, Desktops, All-in-Ones, Displays, Monitors, Accessories). They used to be quality products that were reasonably innovative and attractive (i.e., something you would want to own). IIRC then they were bought by Acer awhile ago. Since then I haven't heard much about them. I do remember seeing some of their post Acer machines: clunky, unimaginative looking, poor build quality. However, in all fairness I haven't seen any of their computers since then. Others on the list may have more current views/perspectives.