A wiki and forum have been set up at a new domain:
mudstandards.org
(Edit: April 2015) Warning: Domain name abandoned. That site is now an adult products shop.
Currently various client and server developers are contributing ideas to the forum. In particular, various people from IRE, myself (MUSHclient), Zugg (cMUD), the Mudlet developers, as well as Lasher from Aardwolf.
The forum is currently inviting people with experience in coding MUD clients or servers to join the forum and contribute to the discussion.
More details are in the post from Jeremy Saunders here:
http://www.topmudsites.com/forums/mud-coding/6006-mudstandards-org.html
At present membership is by invitation only. If you want to join, register for the forum and send Jeremy an email at jeremy@mudstandards.org explaining who you are.
This forum is not intended for low-level details like "how do I get the MUD to compile" but rather to discuss present and future standards for MUD development. For example, a discussion is starting up about the ATCP protocol, which IRE have now released as an open format, so other MUDs can use it as well.