Sony announced its first pair of entries into the rapidly-crowding tablet market.

Dubbed the S1 and S2, the Sony tablets offer drastically different form factors from each other. Reminiscent of Apple's iPad, the S1 features a 9.4-inch display, while the S2 channels Nintendo's DS and Kyocera's Echo with a pair of 5.5-inch displays in a clamshell design.

This design is particularly relevant for reading digital books whose content is displayed on screen as two pages side-by side, said Consumer Products Deputy President Kunimasa Suzuki.

While Sony has yet to release the full list of specifications for the device, the company did reveal that both tablets will run on the Tegra 2 processor, the same one present in Samsung's Galaxy Tab and Motorola's Xoom. Both tablets will also run Android 3.0 (Honeycomb) and offer Wi-Fi, 3G, and 4G connectivity.

Content plays a major role with S1 and S2. Qriocity, Sony's streaming media service, the Reader Store, and the PlayStation suite will all be supported by the devices.

For Sony, the latest competitor to announce its own tablet entries, creating tablets with unique form factors is central to the strategy of countering Apple's iPad.

But the existence of the tablets isn't much of a surprise. Sketches of both the S1 and S2 leaked in February, giving consumers an advanced look at products that Sony had up until that point only hinted at. Sony says that the design and specifications of both devices are subject to change.

Both tablets will be released this fall, months after comparable products from HP, RIM, and Motorola will have already been available.