Do you know anything about this? I'd like to write some mods but I can't dig up any information about the addon support. Some say that it is not planned. Any information?
Currently, Guild Wars 2 does not support addons, and no official announcement has been made by ArenaNet as to whether support for addon development will be added in the future.
Here is a quote from Eric Flannum, who is the lead game designer for Guild Wars 2 (from December 2011):
We won't be allowing people to mod the game itself directly no. We feel that this encourages people to play the game in such a way that gives them an unfair advatage over those who don't use mods. However we understand that many people enjoy modding games and are looking into ways for people to build things for the game in other ways. We'll have more information on this sometime next year.