ObjectiveResource: It's iPhone on Rails

ObjectiveResource (or Github repository) is a framework for iPhone developers that allows you to easily interact with Ruby on Rails applications. Essentially it’s a port of Rails’ own ActiveResource – a library that enables RESTful communication between apps and serializes objects for transit. In this way, it makes it easy to interact with Rails apps (and other apps that support the same RESTful XML or JSON protocol) from iPhone apps in both directions.

There’s a solidly produced 6 minute screencast to get you up to speed quickly along with some brief Getting Started documentation. A sample application is provided that enables you to be up and running quickly, especially since it includes both an iPhone app and a Rails app.