I have no numbers to back this up, but based on personal experience, and anectdotal evidence, I would say that a lot of Mac users are probably using some kind of multi-client IM application like Adium or aMSN. That said, I believed until quite recently that everyone used Messenger identities, only to find that in the U.S., AIM is much more popular. That sort of leaves Yahoo! Messenger out of the picture, but perhaps their newly released 3.0 Beta can change that.
The new beta brings a number of improvements, including support for adding Windows Live contacts, which has been available on the PC version of the software for quite some time. Yahoo! Messenger also now boasts some of the same VOIP features that Skype offers, including receiving and calling out to landline and mobile phones, call forwarding, and voicemail services, all of which are available for an additional fee.
It also introduces stealth settings, which is a selective invisibility filter, meaning you can appear offline to specific, individual users, and remain online for everyone else. I call this “Adultery Mode.” Shame on you if you use it. Shame.
You can also share huge files, up to 2GB, send SMS messages, and broadcast live video to more than one user at a time. As an IM client, Yahoo! Messenger does present some nice extras, and its basic functionality is straightforward and, unlike AIM, not overly distracting visually. Best feature of Yahoo! Messenger for the Mac? The giant, extremly happy smiley face in your dock. Still, I’m definitely not giving up Adium anytime soon.