Code Coverage Plugins with Maven 2

AFAICT, the cobertura-maven-plugin (versions 2.0 and 2.1) doesn't work and neither does the emma-maven-plugin in Mojo's sandbox. Has anyone had any luck with either of these plugins? Is there an open source code-coverage plugin that works with Maven 2? I know about Clover, but that's not open source.

Using Emma and Cobertura with Ant seem to work great.

Thanks,

Matt