I recently had some time to spend in Eclipse IAM, working on improving the WTP support.
Version 0.11.0 already had good support for WAR projects, including war overlays (which was a bit tricky to implement in Eclipse). Now the last builds of the coming 0.12.0 version have EAR support.
You can import your Maven EAR projects and Eclipse will recognize the Maven-generated application.xml and configure automatically the dependencies to the other WAR projects opened in the workspace, with no extra configuration from you. And from the usual WTP "Run in Server" wizard you can run the EAR project and all associated WAR files in your favorite application server.
You can install the development builds of 0.12 from http://q4e.googlecode.com/svn/trunk/updatesite-dev/ until it’s released, and check the installation instructions for requirements or if you have issues. For help and feedback, we have a newsgroup at Eclipse.