> Is there a way to deploy ruby at a fixed version and not
> require a formal setup program?

AllInOneRuby [1] creates allinoneruby.exe, which contains
ruby.exe, its DLL's and the standard library. No site-lib
files, no gems.

Another approach for distributing Rails applications:

Freeze your Rails application, copy the dependencies and gems
to lib/ in your Rails applications and use AllInOneRuby to
build a _big_ ruby.exe. ZIP it and ship it...

For example (not tested...):

 $ rails -f your_app
 $ cd your_app/

 $ cp -af /usr/local/lib/ruby/gems/1.8/gems/sqlite3-ruby-1.1.0/lib/*
lib/

 $ wget
http://www.erikveen.dds.nl/allinoneruby/download/allinoneruby.rb
 $ ruby allinoneruby.rb

 $ ./allinoneruby_linux script/server

gegroet,
Erik V. - http://www.erikveen.dds.nl/

 [1] http://www.erikveen.dds.nl/allinoneruby/index.html