Fastr – A Web Framework for Ruby « chris moos's blog
The core of fastr runs on an EventMachine reactor, which is basically just a big event loop. EventMachine is very capable of maintaining thousands of connections in one instance. This is great when you want an application that supports Comet and chunked responses. There is very minimal overhead in having thousands of connections that have occasional data flowing through.
In the talk he discusses the state of the Ruby VM and why we should standardize an asynchronous Ruby stack which takes advantage of Ruby 1.9, Fibers, and non-blocking database drivers to make Ruby (and Rails) more scalable.
I think the Ruby community needs to give threads another chance: ensure their gems are thread-safe and use Actors when needing to write safe multithreaded code