(...)
I find it quite amazing.
Yep. Me too.
Another interesting concept is the one of the Lenovo IdeaPad U1 Hybrid:

It's basicly a notebook but you can take of the screen. Inside the case of the screen is a complete second system and thus you can use the screen as a tablet/pad.
Some more info:
http://www.engadget.com/2010/01/05/lenovo-ideapad-u1-hybrid-hands-on-and-impressions/About the weTab: They claim to produce that kind of a product but they have been claiming this for a long time now and its still not out on the market.