To use the maven grails plugin
First create a project (or see how to generate a pom for an existing grails project)
mvn -DgrailsHome=d:\install\groovy\grails-1.0-RC1\ grails:create-app
Then cd to the directory containing the new project and create a pom
mvn -DgroupId=com.summitbid grails:create-pom
There's no longer a run-app target for the mvn plugin but you can test it with:
mvn grails:test-app