title: Subsonic 3 ActiveRecords Update Dirty Columns are always empty
body: <p>Any idea why this is happening? The issue was posted here:
  <a href="https://stackoverflow.com/questions/1138102/n-tiers-with-subsonic-3-dirty-columns-collection-is-alwayes-empty-on-update/1139976#1139976">N Tiers with SubSonic 3, Dirty Columns collection is alwayes empty on update</a></p>