[getsat]

If you're on a mac, you already have rails and ruby 1.8.6 (osx 10.5) or 1.8.7 (osx 10.6).

Just sudo gem update to get the latest version and you're good to go.

[drnicwilliams]

ruby 1.8.7 is required for Rails 3; so Leopard/10.5 users need to install ruby 1.8.7 manually to get started as if they didn't have ruby installed at all, I think.

[rohitarondekar]

Actually ruby 1.8.7 is required to install ruby 1.9.2. Rails doesn't need 1.8.7 and works fine with just ruby 1.9.2 installed.

  ruby - Ruby itself is prerequisite in order to build Ruby 1.9. It can be 1.8.

source: http://redmine.ruby-lang.org/wiki/ruby/DeveloperHowto#label-...

[getsat]

If you install via RVM, you don't need a system ruby or anything else installed for bootstrapping.

http://rvm.beginrescueend.com/rvm/install/

http://rvm.beginrescueend.com/deployment/system-wide/

[getsat]

Good point. I've been on 1.9 for so long I'd forgotten about the 1.8.7 requirement for Rails 3.