MacityNet.it and one of its readers found that TCO Development maintains a listing of certified monitors and a simple search for Apple's certified monitors brings up a new entity:
Apple Model A1038, "Cinema HD Display", 20.1", Certification Date: 2002-11-21
Rumors of a new Apple LCD line have persisted since December 2001, with expectations of a new mid-range LCD to fall in place between the current 17" and 22" offerings. Our LCD Rumor summary from September of 2002 recaps the rumors until that time.
Apple's 15" LCD was dropped from Apple's online store in October 2002, which fueled further expectations for an update. Based on this information, it appears a new 20 inch display is in the works, with certification obtained in November, 2002.