Files Tested
When you invoke PMD, you can choose whether you want to run it on the
current file or all the files in your project.

Rules
You can select which rulesets you want to use when you run the PMD plugin.
Currently the "imports", "unusedcode", and "basic" rulesets are selected
automatically.  These rulesets catch things like unused local variables, empty try blocks,
unused imports, and so forth.

You can view all the PMD rules with examples and details at
http://pmd.sf.net/.

Future Plans
Continue to respond to the Gel community's feedback