The Swedish company, PrintDreams Europe AB is your hand and communicates via Bluetooth.
The PrintDreams device uses RMPT (Random Movement Print Technology) to print without requiring a mechanical device to move the printer across the page.
The basic idea is that you have an ink resevior, jet, and the printer intelligence in a hand held device, and you "paint" the page back and forth with the device and it will deposit ink when your hand is in the right place.
By using location sensing techniques, it is able to determine where it is located on the page (presumedly after you give it a signal in a corner or edge) and it then does the rest of the work as you move it back and forth.
Unfortunately, I can't find anyone who is selling them, so we are unlikely to see them any time soon.