We have quite a lot of possibilities to get our webcams to work (like cheese, VLC, kopete and more). Also, there are quite a lot of instant messengers out there, like aMSN, pidgin, eva. They all support one or more different protocols, only a few of them support QQ, the most popular IM protocol in China (for example eva, pidgin and the new QQ messenger for Linux by Tencent, the inventor of the protocol). Some of them don't have webcam support (for example eva, pidgin and the new QQ messenger for Linux), others do (like kopete ...).
However, I could not find a single working solution to have a webcam chat using QQ protocol. So either use another messenger (and be unable to contact your QQ buddies) or talk to your friends (and be unable to see them). OK, QQ is not very popular outside China, but even if not all of the 1.3 billion Chinese use webcams, I think there are still quite a lot of people interested in this feature.