All jboss projects that I know of have eclipse IDE settings in SVN. The idea is, that you can checkout a project, import it into Eclipse and start with what you actually want to do. Is there any particular issue with this?
I run mvn eclipse:eclipse to generate the eclipse projects and therefore I always have a lot of modified eclipse project files in my working copy. In this special case it would be more comfortable to have them ignored.
So generally I am okay with checked in project files but I think mvn eclipse:eclipse would be a good alternative to ensure a eclipse "quickstart" and a clean repository.
Use m2eclipse, the eclipse files are configured for that.