SOE will be officially sunsetting the game on March 8th, 2013. Until that time, however, the servers will remain up-and-running for any players who want to have one last hoorah before the game takes its final bow. Membership billing, however, ended yesterday, February 1st. Any players who still had time on their Platinum Memberships as of that time will receive a "pro rata refund for any time remaining on [their] Bullet Run subscription[s]" from SOE. The full details can be found on the game's official forums, and we wish the best of luck to the game's dev team in its members' future endeavors.
[Thanks to Jack Pipsam for the tip!]