ZDC Controller described airspace entry event when nearby military facility failed to fully coordinate photo mission operation with airspace owners.

Narrative

A photo mission PA31 was being worked by a military facility in W-386. The aircraft was on a two hour photo mission; with random points along its route of flight in the vicinity of ATR and SIE. I was working the SIE sector when a Controller working the SBY sector just south of me called and asked if I had received a point-out from the military facility on an aircraft in my airspace at FL215 squawking XXXX. At this point; the aircraft was 10-15NM NE of ATR; and was tracking northwest very slowly. I told the SBY Controller that I hadn't received a point-out; and thanked him for making me aware of the situation. I; in turn; coordinated with the CYN Sector Controller next to me as the aircraft was headed toward his airspace. Upon completing the coordination that needed to be done at that time; I called the military facility to get more information on the aircraft. I was told the aircraft was in a slow climb to FL220; and that it would be turning back toward W386 shortly. The aircraft never got up to FL220; so I called the military facility back and let them know I would be protecting for the block; FL210 through FL220. This section of airspace can be extremely busy with aircraft climbing southbound out of ACY; aircraft descending into the Washington Metro area from the east; PHL departures climbing southbound; and PHL/ACY/JFK arrivals descending northbound. At the time; traffic in the area was light; but this definitely could have caused problems had that not been the case.