The S1 is the tablet whose unconvential design was revealed early by Engadget. It has a back panel that tapers downward, which is supposed to make it more comfortable, and a 9.4-inch screen. The S2 is the DS of tablets, with two 5.5" screens in a clamshell case, allowing one screen to be used as a soft keyboard.
Both tablets will feature PlayStation Suite, so users will be able to play selected PSOne games on the devices, albeit with virtual controls. Both Sony Tablets (in a rare moment of sensible naming convention, "Sony Tablet" is the name of the line) will be out this fall globally. Check out a brief video after the break -- there's a little Crash Bandicoot in it for you.