I'm pleased to announce the release of Radiant CMS 0.5. To get started you can install Radiant via Ruby Gems like this:

% gem install --include-dependencies radiant

As of right now the gem doesn't look like it's propagated to the gem
server yet, so may need to wait a bit to use Ruby Gems.

You can also download Radiant in Tar or Zip format on the download page:

http://radiantcms.org/download/

Let me know if your run into any difficulties.