The Shards Online website shows off plans for a sandbox MMORPG from Citadel Studios, which includes former Ultima Online developers (thanks Ant via Slashdot/Polygon). There's a recent interview on the topic on Stratics, discussing the twist that this will be a player-run game, as they describe on their website:

Shards is a sandbox RPG in development for PC by Citadel Studios. In the multiplayer online game players can fully customize their experience. Collaboration will determine how the world evolves.

Explore an ever-expanding universe with deep lore and dynamic environments.

Employ Shards' unprecedented modding capabilities. Connect servers, create and run your own MMO, set your own rules, and play how you want to play.

Shards will change the face of multiplayer role-playing games and give players more power than ever before.