Six Apart announced today that Movable Type is now open source. They say that MTOS has every feature in Movable Type 4.0, which I think is a change. It'll be interesting to see if/how this changes Movable Type's share in the blogging community, since WordPress has always been able to wave the open source flag. I also might go and take a look at the source, which I've never examined because I knew there was no reason to.