It would be really stupid (for a JS library) to cut off any browser with market-share above 1%, especially IE6 which won't go below 1% until maybe 2011. You can be sure, they won't do that.
The big sites (Youtube, Facebook, ...) are doing a good job in asking their visitors to upgrade, but IE6 is (reportedly) big in companies where the regular employee cannot just upgrade if he wants to.
