An article from Garrett Rooney just appeared at OnLamp.com
you can read it at
http://www.onlamp.com/pub/a/onlamp/2004/11/18/extending_ruby.html

As you may understand it talks about how to write C extensions for ruby.
It's great to see more ruby in online magazines, who's the next one ? :)

PS
I'm not related to the author or the page, I just found it and noticed 
the author is not a frequent writer here, so I forwarded the notice :)