Thus far, I haven't seen any evidence of the Chinese directly supporting bin Landen or the Taliban with military technology/know-how. Nevertheless, it is worthy to keep on eye on them as they were uneasy about the US getting into the area. Further, I wouldn't classify them as very supportive on the war on terrorism. They say they are but really haven't done anything about it, other than asking for quid pro quo deals (such as we lay off Taiwan and/or support them taking out whoever they deem to be a terrorist - such as those in their Xinjiang province).
Finally, the Chinese have been heavy supporters of Pakistan. Their support has ranged from looking into setting up a deap sea port at Anwar (sp?) to providing missile technology (probably also assisting them in their nuke program). There is still friction between the US and China over China's proliferation of missile technology to rogue states. Just recently, the CATO institute classified China as a terror sponsor. Several non-proliferation talks have also been held between the US and China.