First lookUlteo gives you access to a full-fledged KDE desktop hosted on the company's own servers while taking care of the behind-the-scenes stuff.
Looks promising provided the speed is there like you would get with a normal desktop.
All in all, Ulteo looks promising, and it offers a few important advantages compared to Web-based office suites like Google Docs and Zoho. Using Ulteo, you can work on documents in their native formats, so you don't have to waste time converting them back and forth and dealing with post-conversion issues. Ulteo also offers familiar environments and applications which are not limited in any way. This means that you can use your favorite extensions with Firefox and OpenOffice.org as well as transfer user settings from your desktop applications. Add to this the ability to mount shared folders and servers, plus share desktop sessions with other users, and Ulteo begins to look like a tempting proposition.
Only problem is its invitation only currently ;-P