Thin is a Ruby web server that glues together 3 Ruby libraries:

1. the Mongrel parser, the root of Mongrel speed and security
2. Event Machine, I/O library with high scalability, performance and stability
3. Rack, a minimal interface between webservers and Ruby frameworks

So, Thin is the new dog in town. Did I mention that Thin is fast and flexible?

Thank-you Marc Cournoyer !