I tried to start a machinima related festival calendar on google calendar. Anyone interested in participating should contact me (it's open).
This is the calendar, the RSS feed is here.
Remember, it's a start. The more people commit to it, the more useful it gets.

And by the way, July 31st is the deadline for the Backup festival in germany and the Animatu digital animation festivalin Portugal. Today is the deadline for the Bitfilm Festival!