“As Ruby experiences increasing success, developers are seeking to integrate their Ruby applications with applications written in other languages. Rails provides excellent support for Web services. This article introduces Web services in Rails and focuses on a strategy known as Representational State Transfer.”
A good explanation of REST here:
http://www.xml.com/pub/a/2004/12/01/restful-web.html
And how to implement it on Rails here:
http://www.ryandaigle.com/articles/2006/06/30/whats-new-in-edge-rai…