Thanks! I'll be writing a blog post on the tech shortly (actually moving right now -- on the road but saw our press release pop up), but a quick rundown: at the core is Pylons, with a bunch of custom modules for making sqlalchemy nicer, handling forms in a sane way etc; on the frontend, it's your standard HTML and CSS, but uses "pyvascript", a Python->JS compiler I wrote for this, which supports real macros. I spent quite a while building up the framework to simplify the development, and I plan on releasing all of it when I have the time.