well I just read the newspaper today with the theme mmorpgs, planeshift was amongst the biggest five with more than half a million users, what they don't know is the number of active users.
here it is translated:
Planeshift:Exiting open source alternative who for once can be played on linux (but also windows and mac). Also here we are in the fantasy genre with knights, forts and battles, it's free for all and still under development. More than half a million plays planeshift.
Checkin' in, hope you're all doing ok