Right on schedule, Valve has released its new Portal 2 level editor. The Perpetual Testing Initiative DLC automatically rolled out to all owners of the action-puzzle game on Steam yesterday. A wealth of community maps is already available on the game's Steam Workshop page. Users can publish their own work there, too, of course.
For a quick sneak peek at the level editor, check out this post on the official Portal blog. Unlike the Hammer editor Valve used to make the game, the Perpetual Testing Initiative editor has a clean, straightforward interface that follows the classic Aperture Labs visual style. (See above.) You can get to it by opening the game and clicking the new "Community test chambers" link in the menu.