Chris Lee has written a blog post which discusses his solution on integrating GWT RPC with Spring 2.x.

The differences from a conventional GWT-RPC service:

• No requirement to inherit from RemoteServiceServlet (or any other class for that matter)
• Addition of the @GwtRpcEndPoint annotation to indicate that this bean is an end point for GWT-RPC
  Automagic mapping of URLs (more on this below)
• Ability to use all of Spring’s DI, AOP and other services on the bean (its no different than any other bean)
• I’ve chosen to use @Controller so that Spring 2.5’s component scanning finds and registers this bean; alternately, @Controller could be omitted and the bean simply registered via XML.