Keep an eye out this weekend for Jennifer Wilbanks on the course with you. She ran a 4:26 in 2002. This year she interrupted her training to take a bus to Albuquerque, but she's had lots of training since then trying to outrun people searching for her, and then the media.
Good luck, everyone running in Chicago!
Update: It looks like Jennifer was a DNS. No results for her in the finishers' database.