What RESTful means? I found this document : RESTful Rails development is very clear to express this point. And It is also quickly to test it in Rails. Soon you will find the amazing of RESTful. It just used HTTP GET, POST, DELETE, PUT to manage the resource and some likes JDBC CRUD implement. And more it is a new RPC implement. It has been used widely in web service. So a web service can be invoked by RESTful URL. And I think it make web service more powerful. In some traditional web application, for example a struts or JSF application, RESTful just provides nice URL format.
But obviously RESTful will be more important when application need to invoke 3rd party functions