Well, I’m upset. We’ve been talking about this one for a year, and someone’s gone out and done it. Check out http://mercury.idavidson.net for more info.
In my opinion, this has been a big hole in the Sametime product. Many of the corporate customers I’ve talked to have resisted an enterprise Sametime implementation because some group in the company always had Macs. While this is not a complete Sametime client yet (seems to only handle the IM portion at this time,) I’m really glad to see this niche being covered. Just wish we’d done it first 😉