OSX 10.5 comes with Ruby 1.8.6 I believe, but I see a lot of tutorials that recommend installing the latest version of Ruby from source. I've done this in the past and it's caused minor issues down the road if I install something which expects Ruby to be in the default location and it's not (Phusion Passenger pref pane, for instance).
What I'm wondering is if the default version of Ruby is good enough to use for development purposes, so there's no conflicts or multiple versions of Ruby floating about? Obviously the default Rubygems and Rails versions would need to be upgraded, but I'm specifically wondering about the default version of Ruby that comes with 10.5.