Google Chrome OS Tablet - still a mockup, but looks good
Looks pretty exciting (OS elements), but as of yet of course, it is just a mockup and a few weird videos. I think Google are on the right track though: Chrome is better than any flavour of Windows or full-fledged Linux for a portable computer. Love the floating keyboard, but cannot imagine how well that would work for a small screen.
Problem other tablets face: they work with native hardware on someone else's software. Apple have finally made their decision not to license their OSes worthwhile.
More info here: Google Chrome OS tablet – Polished pad?