When running my GWT application (gwt 2.0.4) in hosted mode, calling RPC methods running on remote Tomcat, I get GWT serialization exception:
INFO: GwtRpcEven
I've been having the same problem. The only solution I see, is to make sure you have the same .gwt.rpc files on both sides.
That means, everytime you start or reload Dev Mode, you have to replace the old .gwt.rpc files deployed on your web server with the newly generated ones.
Or you point the Dev Mode war output directory to the web server context. And make sure the web server has auto-deploy turned on. So every time the files are changed by Dev Mode, the web server automatically reloads the files.