Tornado is an open source version of this web server and some of the tools we
use most often at FriendFeed.

The framework is distinct from most mainstream web server frameworks (and 
certainly most Python frameworks) because it is non-blocking and reasonably 
fast. Because it is non-blocking and uses epoll, it can handle 1000s of 
simultaneous standing connections, which means the framework is ideal for 
real-time web services.

WWW: http://www.tornadoweb.org