A source tells Transnote from RenegadeGenerals that the World Editor won't be released before Generals. "One of the biggest reasons was that the editor requires the models/textures that are part of the game files to operate correctly." The editor will be shipping with the retail version of the game however.
Then again, Amer has made the following forum post about the editor:
We're still waiting on approval to release the World Builder editor online. As I mentioned in an earlier post, I can't give out a firm release date because I don't have one. Once we get any new info, we'll update you. I know you've been waiting a long time for it, but it won't be long now.
Nothing too much new there. I guess we'll just have to wait and see.