I'm re-posting this message for two reasons:
  1. We have new committers on the project who may have missed it.
  2. The previous preferences file didn't import correctly (my previous "testing" of this produced false results)
This is all explained in a DNA wiki page (http://wiki.jboss.org/wiki/DNA/Development), including why we supply these files, but in summary:

There are 2 files in trunk that all developers need to import into their Eclipse IDE to help ensure the quality of our code and to avoid a slew of non-structural or style-related changes appearing in the SVN history: