Mizuno is Webserver for JRuby on Rails.
I looked for different options to run my JRuby App. After some googleing I found Mizumo. It was very easy to install:
jruby -S gem install mizuno
and very easy to start. Just go into the root directory of your rails app and exec.
or if you want to start on Port 80.
sudo mizuno --port 80
Mizuno is the fastest option for Reck applications on JRuby:
Mizuno: 6106.66 req/s (mean) Jetty (via jruby-rack): 2011.67 req/s (mean) Mongrel: 1479.15 req/sec (mean)