Peter Cooper’s post on the lack of a ‘mod_ruby’ is dead on. I am working on a site with millions of hits per month and i couldn’t even begin to credibly suggest that we do any ‘production’ work in ruby.
It is not (just) that Rails isn’t reliable enough. Deployment isn’t brain dead enough. You have to run mongrel, tune the number of instances, then run monit and have it restarting mongrel instances. Then have something or someone watching monit when it fails to restart mongrel every month or so.
Deploying rails requires a significant amount of brainpower from an above average engineer to design the deployment. PHP requires only a rudimentary understanding of FTP.
http://brainspl.at/articles/2008/02/12/what-do-you-want-to-see-in-mod_rubinius