There's some talk on how Apple releasing Mac OS X on x86 would affect Linux.
Mac OS X, is based on the Darwin kernel which is a derivate of FreeBSD. Here is something from KernelThread that explains the architecture of Mac OS X.
The first version of Darwin, 0.1, was released on March 16, 1999 as a fork of a developer release of Rhapsody. Although Darwin is an operating system in itself, it can be best understood as a collection of technologies that have been integrated by Apple to form a major, central part of Mac OS X. Critical application environments of Mac OS X, such as Cocoa and Carbon, are not part of Darwin. So isn't Aqua, the overall GUI of Mac OS X (including the Windowing System), and several other components.
More about Darwin's use by Apple:
Darwin 7.0.x (corresponding to Mac OS X 10.3.x) consists of over 250 packages. Many of these are Apple packages (including the Mac OS X kernel and various drivers), while the others originate from *BSD, GNU, etc. Apple has leveraged a lot of existing open source software by integrating it well (usually) with their system: apache, bind, binutils, cvs, gcc, gdb, gimp_print, kerberos, mysql, openssh, openssl, pam, perl, postfix, ppp, python, rsync, samba, and many more BSD/GNU/other packages ... are all part of Darwin. In many cases, Apple has made important modifications to open source code to optimize/adapt it to their platform (consider gcc and gdb). Moreover, even though one can always configure and control such software "as usual" (editing their configuration file in vi or emacs, say), Apple provides simplified user interfaces that work well for at least the not-so-contrived cases.
And get this: Darwin runs on both PowerPC and x86 platforms!
And to end it all, I leave you with something from Apple Developer Connection about Darwin:
Apple's open source projects allow developers to customize and enhance key Apple software. Through the open source model, Apple engineers and the open source community collaborate to create better, faster and more reliable products for our users.
Beneath the appealing, easy-to-use interface of Mac OS X is a rock-solid foundation that is engineered for stability, reliability, and performance. This foundation is a core operating system commonly known as Darwin. Darwin integrates a number of technologies, most importantly Mach 3.0, operating-system services based on 4.4BSD (Berkeley Software Distribution), high-performance networking facilities, and support for multiple integrated file systems.
Since Apple has now officially confirmed that they are going to release Mac OS X for x86, thus bringing their OS to the reach of many more open-source developers, do we see troubled waters for Linux ahead?
I guess so! But it would be interesting to see how the Linux community reacts. And if they do in fact release something around the same time Leopard and Longhorn come out, well, as I said, 2006 is going to be one helluva exciting year!