After about 45 minutes of frustration trying to work through some maven exercises in the Sonatype book I kept arriving at the following message:
1Reason: Not a v4.0.0 POM. for project org.apache.maven.plugins:maven-site-plugin at /Users/edgibbs/.m2/repository/org/apache/maven/plugins/maven-site-plugin/2.0-beta-6/maven-site-plugin-2.0-beta-6.pom
I had the sample code downloaded and got the same error, so I investigated possibly not having access to the maven [...]