I also found Nick Johnson's (google guy) post on this to be very useful. Honestly, his whole blog is useful - App Engine tips from a guy on the inside.
http://blog.notdot.net/2009/9/Custom-Datastore-Properties-1-DerivedProperty -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To view this discussion on the web visit https://groups.google.com/d/msg/google-appengine/-/Si2ySLfz_noJ. To post to this group, send email to google-appengine@googlegroups.com. To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en.
