Free PDF Guide to Adobe Flex 3 on Rails 2
DZone has released a new entry in their "Refcardz" series (short PDFs that rapidly walk through a single topic) called Flexible Rails: Flex 3 on Rails 2. It was written by Peter Armstrong of Ruboss and covers how to use Adobe's Flex technology along with a Rails 2.x application. It's well designed and packs in a surprising amount of information, example code, and diagrams in its six pages.
(Note: A brief(ish), free signup process is necessary to download the Refcard unless you are already a DZone member - which is well worth it, DZone is a great resource for programmers generally.)