It's more of a commonsense rule, Larry - generally, a character is considered to be an ubermunchkin if he's carrying items/buffs/etc which are obviously unrealistic. In servers with no ILR this would obviously extend to weapons which have a level limit of 30+ (eg a +5 Vorpal with 2d6 of Acid damage and Vampiric Regeneration and +10 to Strength). Obviously doesn't pass the commonsense test.
Even within the level20 limit there are ways to get around this. An example would be a level 20 fighter carrying multiple Rods - Rods of Horrid Wilting, Rods of Harm, Rods of Time Stop, Rods of Storm of Vengeance, etc. that allow him to cast up to 50 spells of each a session, which make him something like a level 20 fighter/level 20 sorcerer.
It's that kind of stuff that is obviously a joke.
[ 09-13-2003, 12:40 PM: Message edited by: Memnoch ]