maxim / off_github

I'm trying to install this gem after seeing the 16th episode of RubyPulse [1], but gem installer tells me it can't find the gem:

inkel@earthsea:~$ sudo gem install off_github
ERROR: could not find gem off_github locally or in a repository

So the logical was to check my gem sources:

inkel@earthsea:~$ gem sources
CURRENT SOURCES

http://gems.rubyforge.org/
http://gems.github.com/

I don't know what I'm doing wrong, maybe it's hosted in gemcutter?

My system is a Kubuntu 9.10, with rubygems 1.3.5. Thanks.

[1] http://www.rubypulse.com/episode-0.16_off_github.html