Hmm -- this is really interesting.

Ten days ago, Facebook open-sourced the Tornado web server.

Written in Python, this is an open-source version of the implementation of the FriendFeed realtime API. Tornado is designed to handle large number of simultaneous connections and to easily allow the implementation of REST-style interfaces using GET or POST.

Another thing that's interesting is that it supports a large number of authentication backends, including Google OpenID/OAuth, Facebook Platform, Yahoo BBAuth, FriendFeed OpenID/OAuth and Twitter OAuth.

These two things combined make an excellent framework for efficiently delivering user-based web apps.

More investigation to follow!