MBPro:shovell myname$ ruby script/server => Booting WEBrick => Rails 2.3.8 application starting on http://0.0.0.0:3000 => Call with -d to detach => Ctrl-C to
The mongrel gem can do this easy.
gem install mongrel
Then you should be able to use
mongrel_rails start -d
-d for daemon mode.
-d