It's my opinion that there is no tablet market. There's simply a market for iPads. Those are entirely different things, but that hasn't stopped many companies from trying to pull even.
The latest to try is Sony -- who hopes not to follow the footsteps of HP and Blackberry, both of whom have failed mightily (Blackberry just hasn't acknowledged it yet).
Sony's Tablet S is due out September 16th. There are several versions, including one that works with AT&T's cell phone network. The device we tested was Wifi only.
Note its odd shape. It's shaped like a book with the cover folded back, the way you'd read a book with one hand. It feels natural. And when you place it on a desk, it tilts towards you. So all in all, a good design.
It feels physically lighter than an iPad, but also more like plastic, both in the body and on the screen. The plastic-y screen means your fingers don't glide the way they do on the iPad. Fingerprints feel like more of a problem, though they're a problem on iPad, too.
The Sony device lacks a "home" button as hardware -- users have to wake it up with the power switch, and the home button is an icon at the bottom of the screen. The screen itself is physically smaller than an iPad's.
Video is very clear, and sound is good using the internal speakers. Front-facing and rear-facing cameras are included. And it works as a remote control with Sony A/V products like DVD players and flat screens.
It runs the latest version of Android, thus it can run Flash, and is upgradable to the next Android OS version (when it's ready).
The Sony Tablet S we tested is advertised as 16gb, but the available memory is actually less because the OS itself uses much of that "available" memory. To augment the memory, there's an SD slot, making it easily and cheaply expandable.