Maven + App Engine + Google Eclipse Plugin
google-app-engine, google-eclipse-plugin, maven
Solution
Depends on what you mean by "compatible" and it depends on what features you're using of GAE plugin. We use the appengine maven plugin http://code.google.com/p/maven-gae-plugin/ and eclipse and they seem to work fine together but we're not using GWT or JDO. As with most things maven/eclipse I find it's best to run your stuff from the command line and just use eclipse as an editor.
Problem
Is there a way I can have a Maven compatible Google App Engine (Java) project that is also compatible with the Google Eclipse Plugin inside Eclipse? Thanks! EDIT: Native support for a Maven plugin now: https://developers.google.com/appengine/docs/java/tools/maven