In the J2EE world Spring-MVC has become a popular model-view-controller framework for web applications providing better separation of concerns than the older Struts framework. In this age of Web 2.0 Ajax is a commonly used to communicate between clients (typically Browsers) and servers. When we looked for a way to use our Spring-MVC knowledge to create Ajax request targets there was nothing that could satisfy a fastidious Spring-MVC developer so we started to think about a Spring Json view which supported all Spring-MVC features.
This way you are able to swap a "classic" Spring application for a Web 2.0 application by just changing the view while keeping the back-end unchanged.
Since release 3.0.0.M4 the springframework provides an own json-view (MappingJacksonJsonView). It's based on the http://jackson.codehaus.org/. For further information see a Comparison of the MappingJacksonJsonView and spring-json view
Spring-Json 1.3.1 released
Spring-Json 1.3.1 added to maven 2 central and project repository