It's another first for the United States Navy, and a big leap forward in the ability and sophistication of unmanned aircraft, as the Navy just recently released video of the first ever unmanned aircraft taking fuel from a tanker. This is called Autonomous Aerial Refueling (AAR) and was the final test objective for the Navy's Unmanned Combat Air System demonstration program.
The unmanned X-47B took over 4,000 pounds of fuel from the Omega K-707 tanker aircraft, using the Navy's probe-and-drogue refueling method. The software and program that guides the unmanned aircraft to dock with the probe are similar to the software that the X-47B uses to land on an aircraft carrier.
You can see a video of the X-47B's refueling below, courtesy of Northrop-Grumman: