Clearly, Blizzard is getting ready for the onrush of reactivated accounts for Burning Crusade by any means necessary.
Will I be able to choose my new realm?
When a realm is chosen to undergo a split, an in-game message at the character-selection screen will prompt all affected players to choose between one of the two new realms being created. The player will be able to make this decision (or change his or her decision) up until the realm-split process has been completed. The realm that the player chooses will be the destination for all characters that the player plays on that realm.
What happens to my characters if I don’t choose?
If a realm is not chosen by the player, each character will be individually relocated to one of the two new realms based on a priority system. The system will first determine whether the character is in a guild and move the character based on the destination of the guild’s leader. If the character is not in a guild, the system will then check if the character is part of an arena team and move the character accordingly. If these conditions do not apply, Blizzard will make the decision for the character(s).
Uh… OK. Yeah, no possibility for disaster here, nuh uh.
Assuming that most of the “server data” is simply tables in an Oracle RDBMS, some bright sparky coder figured out that overcrowding on launch day was a solvable problem. Hey, we can fix this with a smart query!
Too bad it’s doubtful that the server tables have fields for “community”, “friends”, “drama” and “postlaunch decline”. I’m sure those will be hotswapped in next patch.