Andy Ihnatko decided to try his iPhone 3GS, which he had upgraded to iOS 4 with his Apple keyboard dock for his iPad, and surprisingly it actually worked.
As you can see in the video below it works pretty well, and the home buttons, spotlight search, cut, copy and paste all work with the iPad keyboard dock, you can of course use a Bluetooth keyboard with the iPhone running iOS 4.
It seems that the iPhone 3GS won’t work with other USB keyboards using the camera connector like you can on the iPad, although you can use the iPhone in landscape mode using a dock connector extension cable.
via Slash Gear