Keyboards are great optional peripherial devices via bluetooth or USB. Personally I don’t want one on the train, but useful when docked and doing bunches of emails or other documents.
FYI for those who want a keyboard: Brookstone [I think] has a black iPad case [which looks a lot like Apple’s] that has a built in Bluetooth keyboard.
They were distributed at our firm for all the marketing people when they got their iPads.