Rails and Singeltons

The short and sweet: you can not, should not, and will not try to save
information in memory in your Rails environment across web requests.
If you need to save data, use a database, use the session, use flat
files on the disk. Expecting Ruby to "just remember" is pointless here
because 1) yes, development environment reloads everything on each
request and 2) production deploy environments run mutiple instances of
Rails processes so you're never guarenteed to get the same process for
subsequent requests.

Jason

Rails deployment is a huge subject, though in short if you were to use
Mongrel you'd have your HTTP server in front (Apache / nginx / etc)
proxy out to a cluster of mongrels. Thus, each mongrel is a Rails
process.

Personally, I'd say to forego Mongrels / Thins / etc and check out
Passenger: http://www.modrails.com (which does the same thing,
proxying off to Rails processes, but it's all hidden from you).

Jason