I'm very happy to finally announce the long overdue release of SitePlan, my procedural extrusions implementation. There is information about the project here.
Please use the software! The source code is here.
Here's a very clumsy demonstration video of me using the software:
And some of the kinds of things you can create if you invest a little more time.
With any luck I'll have the slides from Siggraph converted into video any week now...