The Entry level is an "alternate reality" level within a UT client. Stuff can be stored there without being garbage-collected. In addition, actors in the entry level can be displayed on the canvas like any other actor. I don't believe that AllActors will iterate through actors outside the level in which whose context it is run. Also, "editactor class=something" will not find actors in the entry level. However, "editactor name=something0" will work.
The entry level only exists on UT clients. I have verified that it does not exist at all on dedicated servers (as it needs to be obtained through a PlayerPawn's GetEntryLevel() call).