I really like how This editor looks. Does it save into a map that is usable right away? as in it saves in the right place, has a picture, a name, a description, ect... also you gotta make it so if someone is playing a map you don't have you can chose to download the map data before joining the game, that is the host allows it.
.... FILE SHARE :O maybe a server were people can upload maps you and download maps, kind of like the halo file sharing, I don't think it would take up that much bandwidth or anything. in the game menus it could almost be like a web browser to a webpage that can be seen in game and out of game, if you choose to download a map in game it downloads to were it is supposed to go and if you choose to download it in your normal browser, it just goes were ever you pick. That would be amazing

it would be a mixture of... Battlezone 2 editor, Time Splitters 2 multiplayer map downloading search thing, Halo's file share system and Far Cry's map downloading when joining game.
All great games

Also another little idea for the editor it's self, the ability to choose weather its indoors or not (like in a cave, or a ship, or a building) when you select this option the sky disappears and the camera flips upside down so it's looking at the ceiling as if it were the ground and you edit i like the ground, the real ground would fade or something so you can see through it while editing the ceiling, maybe an option to set how transparent it is, and while editing the ground the ceiling becomes transparent. This also means you will need a few sets of new textures and objects to match different indoor environments.