Apple StoreLotus Sametime 7.5.1 is a platform for unified communications and collaboration, combining security features with an extensible, open solution that includes integrated Voice over IP, geographic location awareness, mobile clients, and a Business Partner community offering telephony and video integration.

This version extends IBM’s award-winning and market-leading instant messaging and Web conferencing solution by introducing new capabilities that include point-to-point video, integration with desktop productivity applications, a tabbed chat interface, client support for Macintosh users, and server support for the Linux operating system.

System requirements:
• Mac OS X 10.4.6 (Tiger) with JVM 1.5, including patches for PowerPC and Intel
• J2SE 5.0 Release 5 (JVM 1.5).

More info, flash demos, and download link here.