The Maven team is pleased to announce the Checkstyle plugin 2.2 release!

http://maven.apache.org/reference/plugins/checkstyle/

The Maven Checkstyle plugin is a plugin for Checkstyle
(http://checkstyle.sourceforge.net) that allows for code
to be checked and a Maven report produced

Changes in this version:

o The Checkstyle HTML report now provides information on severity.
o Prevent projects who do not use the head check from failing if they
  don't provide a license file.
o Upgraded to Checkstyle 3.2.

Note that this plugin has been tested with Maven 1.0-rc1 and Maven 
1.1-SNAPSHOT. Using it with another version of Maven is at your 
own risks! :-)

You can download the Checkstyle Maven plugin here:
http://www.ibiblio.org/maven/maven/plugins/maven-checkstyle-plugin-2.2.jar

Have fun!