greynode

If you install XCode for OS X 10.5, it automatically comes with a version of rails. This is (generally) not the latest version however, and you must take a few steps to update it. First you need to update rubygems with the following:

macintosh$ sudo gem install rubygems-update

macintosh$ sudo update_rubygems

After updating rubygems, you should be able to update the rest of your gems without a problem (including rails) via the following:

macintosh$ sudo gem update

After that you should be ready to build a rails app.