ZNY Controller described a likely airspace incursion event when information regarding a warning area was not briefed during the position relief efforts and no information was available at the position.

Narrative

Upon taking over Sector 86/65; at the beginning of my shift; I was not briefed that W105 was active; nor were there any usual markings on the display or strips in the bay saying that W105 was hot. I am not sure; but I believe when I took over the sector there was an airplane that I was working in the active warning area. I actually put him on a vector for spacing that made him leave the warning area if he was in it. There might have been one other plane also in the JOBOC Sector going to Boston. I am not sure if either of these planes actually were in the warning area; because I didn't know it was active; so I can't recall. There was a line of weather in the warning area that I was briefed planes were flying around; which leads me to believe planes were unknowingly in the active warning area. The controlling agency of W105 called to tell me that it was no longer active. He didn't say anything about any planes that had been a problem; but he did tell me the initials of the Controller who took the call to activate it and it was not the Controller whom I relieved. It would be nice if there was some sort of automatic display of the active warning areas that Giant Killer or Supervision could activate as they call us; or maybe some way to ensure that the controllers are notified.