/usr/bin/ruby should use the alternatives system
ruby1.8, ruby1.9, and ruby1.9.1 should set up their binaries using Debian's alternatives system, so I can easily choose which one I want. Ideally, the choices for related binaries (rubygems and irb) would be linked to the choice of ruby.
I am interested in this change because I would like to use ruby 1.9.2 (available as ruby1.9.1) for much of my development work, and I'd like to switch to it on my production servers. Of course, all these systems run on Ubuntu.
DistroRelease: Ubuntu 10.10
Package: ruby 4.5
Uname: Linux 2.6.35-20-generic x86_64
Date: Fri Sep 10 01:46:40 2010
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Alpha amd64 (20100906)