His advisor's memoir is also interesting:

"So after Yitang graduated, I told him the normal way of seeking jobs. When I looked into his eyes, I found a disturbing soul, a burning bush, an explorer who wanted to reach the north pole, a mountaineer who determined to scale Mt. Everest, and a traveler who would brave thunders and lightnings to reach his destination. Yitang never came back to me requesting recommendation letters. Apparently, he did not seek a job. Even to the date Yitang announced his monumental result I did not know what was the best for him. Though I was sure of one thing, − he could not survive the life of “tenure-track,” “tenure,” and “promotions”. It was not his type. I regarded him as a free spirit, and I should let him fly."

http://www.math.purdue.edu/~ttm/ZhangYt.pdf