Michael Robertson, known of MP3(tunes).com, Gizmo and Linspire, has launched a 'Web OS' named ajaxWindows. It's not the first one in its category, but as far as I know it's the first one using Gmail for file storage with Google's permission:

"ajaxWindows has partnered with Gmail to provide you with storage using your email for your documents, photos, and files stored on ajaxWindows."
http://www.ajaxwindows.com/apps/windows/content/register.html

I haven't tried it yet and don't know how it works exactly, or how close the partnership with Google is. It doesn't really look googley, but if it works out well it might be another step in the direction of 'Gdrive'...

More about ajaxWindows:
http://www.ajaxwindows.com/apps/windows/content/index.html
http://www.michaelrobertson.com/archive.php?minute_id=243

Maybe "ajaxWindows has partnered with Gmail" does not mean "Michael Robertson has partnered with Google". I won't try it to give out my Gmail info.