It would be great if the violations plugin could mark a build as unstable if the
number of violations in a project increases.

For example if a developer commits code that contains new errors that are found
by findbugs or pmd, and the violations plugin marked the build as unstable,
hudson would email the developer and let them know of the status change. That
way the developer could change his code immediately while everything is fresh in
their mind.

This could potentially catch errors when they first happen, as opposed to coming
back and cleaning them up later.