In the upcoming 1.4 release of Google Web Toolkit, finally all the serialization logic has been removed from the RemoteServiceServlet. The serialization code now resides into a new class named RPC.
This is a small but important change that will allow developers to easily integrate GWT with other server-side frameworks. I am sure that a lot of people (like my friend George who is the author and maintainer of the most popular GWT-Spring integration framework) will be very happy with this change since it will greatly simplify their code.
Robert Hanson has all the details in his blog.