As KeSPA reports, fOrGG's status was set to an amateur on December, the 28th, 2010, which means that fOrGG retired from being a progamer.

fOrGG is probably a very well known terran, especially for beating JaeDong 3-0 in the MSL finals back in the summer of 2008.
Today, however, KeSPA set his status from progamer to amateur, which can only have one reason, his progamer license got revoked after he told KeSPA that he retires.

His performance lately wasn't the best, but he was still in the current MSL season, placed in Group F, where he had to fight the protoss PerfectMan in two days, where he will be replaced by a default win instead of another player.

KT Rolster announced that "We respect player's decisions, but it's disappointing.", while fOrGG himself didn't make an official statement about his retirement up to this point.

Links
fomos.kr - Source (Korean)