It looks like the HP tablet may have been outed - and no, it doesn't run Windows 7 (as Steve Ballmer previously hoped) nor is it doing WebOS (sorry Palm acquisition). It's running on Android, and Engadget has the scoop on the HP Zeen:
The Zeen is a capacitive tablet running a HP skin on top of Android 2.1 -- it won't get shifted to webOS, and it's not clear if it'll get upped to Froyo before launch given the development time required. It has capacitive touch buttons, a SD card slot, video support, and at least some prototypes have cameras with a special webcam app installed.
E-reading is a major focus, and the Zeen has "significant" integration with the Barnes & Noble Nook bookstore and ecosystem. Makes sense, as the Nook itself is based on Android, and being able to print e-books from the Zeen would be a huge differentiator - and a great way for HP to sell more ink.
The Zeen with come in two configurations: a $399 bundle with a new printer called Zeus and as a standalone unit for an unknown price. The Zeus has its own "basic" control setup, but when the Zeen is docked it provides a rich interface to the printing functions -- presumably a web-connected interface like the one HP's been moving towards with other printers.
Hit the link for the full details.