As mentioned before, The JooJoo Tablet. Saw public release in 2010, but the first prototype came out in 2008.
The iPad, really all tablets in general, following and proceeding, all share the same generic design. Know why? Because they're all basically little screens you hold in your hand. For comfort, they have to be thin, they have to be light, and they have to be easy to hold. Any other shape or form would make them too unwieldy. This limits variation, and why you won't see many differences among them even into the near future.
The iPad, really all tablets in general, following and proceeding, all share the same generic design. Know why? Because they're all basically little screens you hold in your hand. For comfort, they have to be thin, they have to be light, and they have to be easy to hold. Any other shape or form would make them too unwieldy. This limits variation, and why you won't see many differences among them even into the near future.