Several high-population servers throughout World of Warcraft have encountered a repeated problem over the last few weeks, which has come to be known as the "instance boss." When a group tries to enter a dungeon, the portal simply does not work. This is accompanied by a chat message: "Additional instances cannot be launched, please try again later."
The comma splice notwithstanding, it's a truly unfortunate bit of timing. Patch 3.2 makes heroics an attractive option again, with every player in the game interested in farming the now-widely-available Emblems of Conquest; prior to that, heroic dungeons and normal raids dropped less-valuable Emblems of Heroism, which had a very small number of potential uses.
Emblems of Conquest, on the other hand, can be used to buy hundreds of items. Now the entire population of the game is once again interested in running instance after instance... and surprise! They can't.
The nerd rage over the issue has reached a fever pitch just as you might expect, mostly owing to the fact that, well, WoW makes more money than God. You should be able to just plug in a few servers and call it a day, right?
As it turns out, not so much.
What's interesting about World of Warcraft is that, due to its sheer popularity, it often confronts issues that other games never even have the chance to consider, and this is one of them. Are there any other MMORPGs that have ever had a problem with having too many players?