Hua Huiqi, a Chinese Christian based in Beijing, left for church last Sunday. It was a special day, because US President George W. Bush was going to be visiting the same state-approved Protestant church as Hua.
President Bush made it to church. Hua did not.
He was arrested by the Chinese police. His crime? Hua is active in the house church movement in China, a movement that is outside the control of the Chinese government. Authorities must have been afraid that Hua would make a scene while Bush was enjoying the "religious liberty" that China offers.
Hua apparently escaped from police custody. His brother says he is in hiding, being cared for by other Christians. The article I've linked to talks about other activists who are under virtual house arrest during the Olympics. It also sounds like they are just generally harassing house churches.
So, if you are a freedom-loving person enjoying the Olympics, just remember that there are a lot of people in China who don't have the same liberties you do. Pray for them, and rattle some cages in Washington. You never know what might happen...