It seems like a pretty obvious hack by player DAVID_GLENFARB, who is currently at level 91 with 81 total games played (and a rise in score of 52 over the past 24 hours). Someone should probably look into this if someone hasn't already. Thanks!
Yup :(
I removed them in the database, and they will be gone from the next update onward.
They're already removed from the fan-made live leaderboard: http://dominion.lauxnet.com/live_leaderboard/