iPad's touch keyboard covers more than half its screen, obscuring most of what you compose. Bluetooth keyboards from Logitech and iLuv are designed to free up iPad screen real estate and make it easier to compose text. I've had a chance to play with them and here are my impressions.
As you can see, the iLuv case makes the formerly thin iPad 2 a bit thick. It closes with a Velcro strap, which adds even more depth. You can see a microUSB jack to charge the battery, which iLuv says will last two days in standby.