Why no mod_ruby?

Interesting article asks why you can’t drop Ruby apps into your LAMP stack ala php?  Don’t miss the comments.

No True “mod_ruby” Is Damaging Ruby’s Viability On The Web

Since PHP, Python (including Django apps), and even Java apps (via Tomcat) can be deployed reasonably easily on an Apache stack with the relevant modules installed, shouldn’t we be able to get mod_ruby doing the same thing?