Blood of Dragons is the only author-approved MUSH based on George R.R. Martin's A Song of Ice and Fire. Play the Game of Thrones and become a part of the history of the Seven Kingdoms:
No. George R.R. Martin has given the owners of the game, Elio M. García (Balerion) and Linda Antonsson (Nymeria), permission to run the MUSH as well as provided them with various bits of (as of yet) unpublished setting information, but he is not involved with the game.
The Westeros network consists of several different sites, including a forum and a wiki, for all your A Song of Ice and Fire needs.