Since Chicago I've seen a few people have already commented on his highly respectable 2:19:01, but I feel like his story is pretty inspiring for the average runner. So here's what I remember 'bout the guy:
HS PRs of 4:26, 9:51, 16:31 XC 5K (ran at FL south course)
2nd in XC at VA's 'A' division state meet, which equates to maybe 30th in all of the state of Virginia. Same story for track, one state title at what letsrun would consider "baby states." Hell, in his senior year he wasn't even his team's #1 guy.
He attended James Monroe University until the program was cancelled at the beginning of his sophomore year. Rather than transfer to another program, Tim moved back home to Fredericksburg and began training towards his goal of being a professional marathoner.
Over the next 3 years, without a team training environment, he knocked his PRs down to 24:00 (8K), 49:04 (10Mi), 1:06:58 (1/2 marathon), and 2:25:19. These times were good enough to get an interview with Hansons and now he's dropped his marathon PR by 6 minutes and is a sub 2:20 guy at 23.
With his youth on his side, you gotta figure he will qualify for at least two Olympic Trials (at ages 25 and 29).