Restful is stateless. The main goals of Restful architecture are scalability, availability and agnotiscs technologies between software (via an common interface). A new Internet draft is out, it names RESTful Authentication Pattern and will help to design your architecture.
If you will deploy this type of architecture, you can read this slideshare which give best practices to design API (a webinar is available too). To design a Restful architecture, you need to design your URI. There is another good document made by Apigee : Web API Design – Crafting interfaces that Developers love [PDF file]
Here is some examples of API architectures:
To conclude, there is a tool to assist you on your development : Rest-client. It’s a Java app (so cross-platform) to test your Restful webservices.