From The New York Times:
Zhao Yan is far from the only journalist now locked up in a Chinese jail for practicing his profession, but we feel Mr. Zhao’s detention especially closely. He is accused of providing state secrets to foreigners, a vague catch-all charge that Chinese authorities often invoke after reports of some piece of public business that Beijing would have liked to keep quiet. Last September, Chinese officials were angered by a Times article that accurately predicted the imminent retirement of a senior Communist Party leader, Jiang Zemin. They may have arbitrarily chosen Mr. Zhao as a target for their anger.
For more about Zhao Yan, see here.