Valve is releasing a puzzle maker for portal 2! It'll be released May 8, and will be integrated with steam workshop. I guess the workshop has been doing really well for team fortress 2 and skyrim (seeing as they're working on expanding it..). It will be available on both pc and mac.
They say it'll be really easy to use, and that we'll be able to create test chambers of all sizes! They're going to release more information next week apparently... but here's their video for it!
I like the videos they make for portal, they can be funny...
You can read more here
at the portal 2 blog.