I've tried using the iPad in its official iPad Dock with a Bluetooth keyboard to be productive. The physical keyboard is only marginally faster than the software one on the device, but the real speed killer is the lack of a mouse. It's just not in my muscle memory to reach up and touch the screen when I want the cursor to go somewhere else, especially when editing a Pages document, or an email. I instinctively reach for a mouse that isn't there. Now, thank's to the iPhone Dev Team, (sorry, have to say it) there's an app for that.
Using the iPhone Dev Team's Spirit software, iPad users can jailbreak their device and allow it to run applications not approved by Apple. (Remember, jailbreaking voids the warranty on the iPad.) Want to add mouse support? Simple. Go to Cydia (the jailbroken version of the Apps Store), and download an application called BTStack. This software contains the Bluetooth profile necessary to support a Bluetooth mouse. Once you have it installed, you're golden. Mouse support is now a reality.
The team that put the software together has created a video of the entire thing in action. You can watch how it works below.