This has also occurred for me in my vanilla SMP server, currently running 1.4.5 with all 1.4.5 clients. The map that will not update (Map #3) happened to be the only map in an item frame at the time of update from 1.4.3 to 1.4.4 and 1.4.5. Screenshot attached is of the map with two item frame markers (green arrows) that have been removed; there are no copies of this map in an item frame, yet the markers still remain and the white player marker is not present.
Map in hand is the entire stack of copies in the world of Map #3. However, you can see that it has not updated since removal of the item frames, and it does not show the player location. The player location would have been very close to the center of this map item.