Anyone know how to use "identicons" with Ruby on Rails?

An "identicon" is a small 9-block image generated using hashed data, like that of an IP address to visually identify users quickly while still preserving user privacy.

There seems to be a couple of variations for PHP, Python etc... is there anything like this pre-packaged for Ruby on Rails? I have looked and been unable to find anything.

There isn't, but it'd make a neat plugin for interested folks.