Rails 2.2 was released on November 21st, 2008. We haven't seen a new release of Rails since the summer, so this should give all you RoR coders out there something to sink your teeth into. As this is an incremental release, there aren't any groundbreaking or major architectural changes from Rails 2.1, and all of your Rails 2.1 code should still work in Rails 2.2.
Before you jump in and install Rails 2.2, make sure you've installed Rubygems 1.3.1 first, since Rails 2.2 needs this in order to install. If you haven't updated Rubygems lately, you'll need to do so before installing the new Rails gem. Use the following command to see which version of Rubygems you have.
$ gem --version
If the reported version it lower than 1.3.1, use the following command to upgrade Rubygems.
$ gem update --system
On some systems, updating Rubygems this way won't work. Of course, it also doesn't help that Rubygems will silently fail, giving you no indication that it hasn't worked, so make sure to re-check the version after running the command above. If it hasn't worked, try the command below.
$ gem install rubygems-update
$ update_rubygems
$ gem --version
