Although the gwt-maven-plugin from codehaus is going through the merge with the gwt-maven plugin from Google Code, I wanted to share with you how building the Ext-GWT mail application with the gwt-maven-plugin from codehaus is a little easier. Please find the code for this second part here
You'll notice the POM file is a little less verbose with regard to configuration and additional plugins (the plugin used to unpack the native GWT lib). There are more default plugin configuration parameters also.
Run a mvn install at the root of the code distribution to compile into a war file. Note that your MAVEN_OPTS environment variable should be set to increase the memory of the JVM.
Creating eclipse project files is simple also. Although I would recommend getting the m2eclipse plugin for Maven projects, you can generate eclipse plugin files by running the following maven command from the root of the code distribution (the directory where the pom.xml file exists):
mvn gwt:eclipse
Stay tuned for more details about using this plugin as the codehaus and Google Code plugins merge!