I've used Ajax chat before with SMF software at 3 sites, it's great.
I couldn't tell by the author's code if he was pulling up & using the software of the original Ajax Chat.
I have a full copy of that software in my hard drive, I use it in a stand-alone chatroom at an SMF site of mine.
However, there was no chatcox or shoutbox added to my WP front page after I enabled the plugin, so I disabled it.
I'll be waiting for comments, thanks.