Over at the Yahoo! Messenger Blog they have announced an update to Yahoo! Messenger for Mac 3.0 beta. The Mac version of Yahoo! Messenger includes webcam functionality as well as most of the features present in the Windows version, with the unique Macintosh feel.
Some of the new features include the ability to set different visibility levels for various friends, just like the windows version, improved stability when running on the same system as Windows Live Messenger and the ability to import your friends who are using Windows Live Messenger.
For more information on this release head on over to the Yahoo! Messenger Blog
You can download Yahoo! Messenger for MacOS X 3.0 beta here
Requirements: MacOS X running on an Intel based mac or PowerPC