I thought it ought to be possible to explain DWR in a single graphic, so I had a go. I think the result gives a simple overview of what is going on, without getting bogged down in how marshalling is done. What do you think?
On the subject of DWR, I've now had 3 requests for logging to use commons-logging so I've cut a 0.6.beta which makes commons-logging optional. If it's there DWR will use it, if not you get Servlet.log as before.
0.6.beta also makes some of the error messages better.
Download the new beta here.