What is going on at 16th and Georgetown?

Via his Twitter account, Curt Cavin is reporting that Indianapolis Motor Speedway President Joie Chitwood has resigned.

I don't have any details beyond that, but Chitwood's resignation would be a big blow to IMS; he seemed to have the track and its events (aside from the Brickyard 400) back on track and growing.

Obviously, more details will follow later.