This feature is scheduled for: Rails v2.3/3.0
In what is clearly a move to make me irrelevant within the Rails community, news has broken about the new Rails metal feature before I had the time to do a proper write-up. (And for the second time in as many weeks, no less). I need to get on my horse here, many apologies.
So Rails Metal is a way to cut out the fat of the MVC request processing stack (and the all the niceties, too) to get the quickest path to your application logic. This is especially useful when you have a single action that you need to run as quickly as possible and can afford to throw away all the support Rails normally provides in exchange for a very fast response time.
While I could throw out some examples here, I’ll let Jesse Newland of RailsMachine do the heavy lifting with his great writeup (a little morsel – his tests have Metal running 25x faster than the comparable controller-based action).
This is definitely an exciting feature to keep an eye on!