One of the quieter announcements coming out of this week's Macworld Expo in San Francisco is the beta release of X11 for Mac OS X. Based on XFree86 4.2.1, X11 for Mac OS X provides the same windowing environment used by a myriad of Linux and UNIX applications. Apple has ported the client and server libraries, and provides headers in the SDK in order to simplify porting X11 applications to Mac.

Because Mac OS X finds its roots in FreeBSD, it is no surprise that Apple is courting open source developers to its Darwin platform. And to make X11 applications feel more at home on a Mac, Apple has enabled support for Aqua window controls and advanced Quartz graphics rendering. X11 applications can run side by side with native Aqua applications and even minimize to the Dock with the "Genie Effect."

"Apple has become the highest volume supplier of UNIX-based systems, and now with X11 for Mac OS X we're making it even easier for UNIX pros to switch to the Mac," said Apple's senior vice president of Worldwide Product Marketing, Philip Schiller. "Mac OS X is really catching on with the UNIX community because of its standards-based approach, familiar tool sets and rich foundation for building modern applications."

The X11 for Mac OS X public beta includes a window server, libraries and basic utilities such as xterm. It can be downloaded from Apple, with additional toolkits and applications available from OpenDarwin.