AOL has released their preview build of AIM with Facebook Chat.
Chat with your Facebook Friends on AIM – Use AIM to chat seamlessly with your Facebook friends. Chat with them in AIM whether they’re AIM users or not.<Right-Click> and "save as" to download the Windows & Mac Versions:Download –> AIM Beta with Facebook Chat (Windows Client)Download –> AIM Beta with Facebook Chat (Mac Client)
. . . or launch AIM Express Flash Based Client