As if we didn't have enough already, Apple has given us one more reason not to use Mac OS X as a server OS.  Add untimely and unclear security updates to the existing list of:

• Intense heat - heat and power management is why Apple switched to Intel.  While you wait for Xserve to catch up with Apple's dual-Intel-core desktop range, buy a dual core Dell PE 850 or IBM x306m - cheaper, faster, quieter, and easier to manage.
• No VGA port or remote console interface, so you must have another Mac to manage it.  Linux web management via Webmin is far more portable.
• Poor performance under typical server load.  If you don't want to wade through the entire article, you can cut to the chase here or here.
• Nowhere near the server software selection of Debian or SUSE Linux.  On Debian, i have access to over 10,000 software packages at my fingertips.  SUSE is not far behind.  On Mac OS X server, i have to build them myself, or use a third-party tool like Fink (which essentially provides Debian's packaging infrastructure for Mac OS X).
• No upgrade pricing from version 10.3 to 10.4.  They also don't allow you to buy software maintenance without first being on a volume licensing agreement, and buying a new license for the latest version.  Linux, on the other hand, is free.