I am just about testing the Karmic Koala which is due for launch next week. There is significant amount of Browser Based Operating System in it- it seems like a Cloud OS and Firefox have been integrated. See the following screenshots-
Note the ability to send email from the toolbar itself- Also the system speeded up considerably after the upgrade was installed. The striking change was in design and folder structure (it seems that they analyzed the usage data in Canonical to decide what design feature to keep and what not to keep)
Here are more views, and yes the Website http://www.ubuntu.com just went for an upgrade maintenance to cope with next week’s heavy rush or downloading.
Caveat- this is just the beta version but 5 days before launch beta version generally stay faithful to design changes.
Visit http://www.ubuntu.com for a better look- I believe dual boot Windows 7 and Koala are supported that helps you with
trying Ubuntu for fun and Windows for your original work.