From Facebook Developer Wiki

RFacebook Official Client

The official RFacebook library 0.8.0 and higher is now updated (August 9th, 2007). Please use this version of the library going forward, as it will have active development in its current state.

• RFacebook homepage with quickstart tutorial and documentation
• RubyForge project
• rfacebook questions & answers site includes rfacebook Q&A and Sightings series and more
• rfacebook questions & answers mailing list/forum - Official rfacebook Forum/Mailing List
• 20-Minute Quick Start Guide for RFacebook - 10 Easy Steps to Create a Facebook App Using Rails (Updated for RFacebook 0.9.7 including the Rails Plugin)

The newest version incorporates a Rails plugin, RFacebook on Rails, which should speed development.