So, by now you've seen the PlayStation Certified Qriocity tablet known within Sony as the "S1." But that's not the only tablet the venerable Japanese company is preparing to launch in 2011. We've been told by a pair of highly trusted and proven sources that Sony is also working on two rather unconventional tablet form factors including a dual-screen Honeycomb clamshell and newfangled Windows 7 tablet slider.

First, let's look at the clamshell model sporting a pair of 5.5-inch displays -- a device first hinted at in a 2010 Sony patent application titled "Electronic Book with Enhanced Features." However, unlike the patent's blocky illustration, we're told that Sony's clamshell -- known as the "S2" internally -- more closely resembles an oval cylinder when closed as depicted in the illustration above. Spec-wise, we're told that it will be very similar in performance to the S1 with a Tegra 2 SoC and WiFi + 3G radio on the inside and front- and rear-facing cameras on the outside. And like the S1 tablet, the S2 will be focused on delivering Qriocity media to the consumer. Sorry, no word on whether the S2 is PlayStation Certified. Obviously, the S2 won't be running stock Honeycomb -- instead, Sony is currently optimizing the Android OS to make the most of those two displays. One source reports having seen Gmail running on a demonstration prototype where the list of messages is displayed on one screen with the body of the selected message displayed on the other. Maps, we're told, will display the map graphic on one display with the detailed turn-by-turn instructions or Streetview displayed on the other. Likewise, the S2 will display a video and picture navigation menu on one half of the clamshell with the selected content blown-up to fill the screen of the other. We're also told that these apps will work in a variety of orientations. Sounds interesting, to say the least. Regrettably, our sources are less than enthusiastic. Click through to find out why.

Unfortunately, both of our sources are cautious about the prospects of the S2. One source claims that the gap between the displays should be made smaller noting that the whole project is being met with skepticism within Sony. Another source calls the S2 an outright "dog." Still, Sony's plan is to ship the WiFi + 3G equipped S2 to the US, Europe, and Japan before the holidays with a $699 targeted asking price.

Last up is a VAIO-branded 9.4-inch Windows 7 slider similar, we've been told, to Samsung's Sliding PC 7 Series and the ASUS Eee Pad Slider. It's design was described to us as "nice" and could easily be interpreted as a followup to the VAIO P series. Unfortunately, the hardware's good looks are undermined by a Pinetrail-class Atom processor. At the moment, the target price is set for $799 but will almost certainly increase, according to one source, by the time the slider is available for retail in the fall (possibly October).

So there we have it, a trio of leaked devices that mark Sony's entry into a soon to be (over?)saturated tablet market. With the exception of the Windows 7 slider, Sony is betting on unique hardware and a custom-built user experience to differentiate its S1 tablet and S2 clamshell from all the me-too Honeycomb slabs launching in the first half of the year -- a real gamble given Sony's notorious reputation for poorly designed UIs and software. Regardless, both of our sources seem genuinely excited about the S1 tablet -- a device that could be very compelling if it can deliver Sony's rich ecosystem of Qriocity and PlayStation services for music, games, ebooks, and video in a unified manner. And that's a big "if."