PuzEdit is a Portal 2 map and puzzle editor, based around the Perpetual Testing Initiative Editor currently built into Portal 2. It comes with all of PeTI's features, with custom package support and is easily expandable.
PuzEdit 0.0.1-889 Alpha release. Contains a very small amount of items, along with some basic features.
Is this still a work in progress?
Yes, it is very work-in-progress, being barely a shell of the final tool.