Possibility of Portal 2 in-game level browser discussed in The Final Hours of Portal 2 app
Geoff Keighley has updated The Final Hours of Portal 2 with a new 2,500 word chapter through iTunes and Steam.
In it, he discusses how Valve were working on: a "Photoshop for test chambers", how it was attempting to create a more user friendly level editor, the possibility of adding GLaDOS herself to the editor, and how Valve's working on an in-game level browser which could eventually find its way onto consoles.
While Valve mentioned it was working on all these goodies, it never confirmed to Keighley whether or not any of it would eventually see a release.
The app update also includes details on the making of the Peer Review DLC.
You can download the newest chapter through the above referenced outlets, and those who purchased the original release of the app can get it for free, otherwise the entire app will run you $1.99.