An included sample application (only 154 lines, including progress bar code) downloads a journal to an SQLite database.
This allows, for example, offline browsing, rapid analysis, or graphing. (Note: these examples use software external to this announcement, and are just mentioned as motivating examples.)
Documentation, downloads, etc. are available from the LiveJournal Ruby module home page.
Or, if you're running RubyGems, you should be able to just run
gem install livejournal. (I don't have much experience with RubyGems, so if there's a problem please let me know.)