I've recently encountered a new MMORTS that is also free, it's called Dawn of Fantasy. It is completely different from any other MMORTS and also looks pretty epic. It has a persistent world which will make for some very interesting RTS PvP. It's appearance is much like that of stronghold, but with many more features and innovations. Check out the trailer if you're interested: http://www.youtube.com/watch?v=539HAMNj8ts
I was also sadly surprised that this game has not been reviewed by onrpg or mmohut but hopefuly they will do a review soon. Please tell me what you think of this game.
gameplay trailer:
http://www.youtube.com/watch?v=ZrkBJT9c7Jg