GWT with RPCs on Tomcat 6

The Tomcat Security Manager has bitten me again.
I'm liking GWT development with the Eclipse plugin. I ran through the StockWatcher tutorial, added RPCs and it was working great in hosted mode, but when I deployed it on Tomcat 6 on Ubuntu 9.04, RPCs failed with the following:
The call failed on the server; see server log for details


New GWT Projects in Eclipse

I had a bit of trouble getting a GWT project setup in Eclipse so that I could use a generated Ant build.xml for creating war packages but also utilize the fancy GWT Eclipse plugin features. The New Web Application Project wizard sets up the GWT project and creates some handy starter app code, but there's no option within the Google context menu to simply create a war. You can deploy directly to Google App Engine which is pretty cool, but I prefer to be able to deploy and run my webapps from my own server so that I know they can be deployed on any Tomcat installation.