I have just rewritten the Checkstyle plugin for Maven (version is now 2.0) so that it supports the excellent Checkstyle 3.1 tool.

The new plugin is currently located in Maven CVS and you need to build Maven from its sources to use it. In other words, it has not been released yet.

Note this new checkstyle plugin for Maven has only been tested with Maven 1.0 beta 10 and is not expected to work with other versions (but it may...)