Mahout Plugin for ruby on rails

I want to use Apache Mahout in my project on Ruby on Rails for implementing recommendations and collaborative filtering. In Particular my requirements are:

1. suggesting related tags.
2. suggesting related articles.
3. based on user's preferences prompt him for review of articles.
4. based on geographical location, and other meta information of a user, suggest him similar users.

I am open to using any other solution (other than mahout) if it integrates with rails easily and fulfills my requirements.