The Maven jMonkey SDK Helper is a helper maven project that can be used to install the libraries necessary to build JME applications with Maven.
$ cd jme3-maven-helper/jme3-thirdparty
$ mvn install
$ cp jme3-maven-helper/jme3-buildhelper/pom.xml $JME_HOME/pom.xml
Now you can build jme3 with maven!
<dependency>
<groupId>com.jme3</groupId>
<artifactId>jMonkeyEngine3</artifactId>
<version>3.0.0-SNAPSHOT</version>
</dependency>