Metagaming
Metagaming in the context of Urban Dead essentially boils down to using Out Of Character perspective or communication methods to coordinate In Character actions.
In its most primitive form, it simply consists of in game characters communicating valuable game information via an out of game medium (e.g. this wiki, internet forums, or instant messaging/email).
Within MMORPGs metagaming is generally viewed as an enhancement to the game's experience. The limited nature of the medium limits the ability to fully immerse one's self as a character because possible character action is rigid and unrealistically defined, lacking the free-form possibility of action apparent in many RPGs. One key aspect of this within Urban Dead is that communication methods which might be possible within the game's universe are unavailable within the game mechanics themselves. This quality leads MMORPGs to be treated as games with roleplaying aspects rather than a roleplaying game.
Controversy
What one person sees as legitimate metagaming another may view as unfair advantage or even cheating. If a metagaming action is particularly powerful, difficult to explain In Character or unusual, it is more likely to be viewed by some as unfair. Unsurprisingly, any complaints there are most often come from those not benefiting from the action.
Some view the exploitation of bugs and quirks advantageously to one's character as metagaming. Others view it as cheating. Often common acceptance of an exploit depends on developer reaction and the spirit of the game. There have been numerous cases where developers embraced bug exploits and revelled in the unexpected use of a game's "quirks" such as rocket-jumping in Quake or skiing in Tribes.
The DEM's DEMON (an intelligence sharing tool) caught some flak for being so close to zerging.
For those who seek full character immersion the term Metagaming may be seen as an insult.