I suggest that we move all the "samples" (integration tests) for the maven 2 plugin to the plugin's project and use the invoker-plugin. This would be similar to how we do the integration tests for the maven archetypes.
This would allow us to create more advanced integration tests in a cleaner way, like when we need to create other artifacts to use in the tests. All this would then not be deployed (and pollute) the Maven (remote) repository. Also, consistency with how we do for the archetypes is good.