(There is a Bluetooth version of this exact same keyboard of exact same size!)
The 7290 and 7100 should
technically be able to support this, however it is unknown at this time. It is mighty useful for those occasional needs when you've got those bigger-than-normal marathon emails; and gives another reason to leave that laptop behind. It could even be used with eOffice to do documents on the BlackBerry!
If not supported yet, all that is needed is a generic Bluetooth HID driver; which should take an experienced RIM programmer only a short period of time to write; and there should be no security problems. The keyboard already exists. All that's needed is a software driver.
I invite you to come to the Hardware forum and join the discussion in this post