I am wondering the same thing. Are there any Mac apps out there that can make the Mac "pretend" to be a BT keyboard? In the same way BluePhoneElite makes the Mac work as a BT headset, I'm sure it's possible anyway.
This would save me from having to buy another bluetooth keyboard!
Are you able to pair both the iPhone and whatever Mac you have at the same time? Or once you're done with your iPhone do you have to repair it with your Mac again?