Ed stated that Mac OS and Linux are probably Y2K compliant. MacOS has been Y2K compliant since its introduction- its method of date calculation is different from that used by most other OS’s. NO Y2K problems here- hopefully!
Someone beat me to it, but I’m going to post anyway, as a long-time Macintosh user. Never get on the bad side of a Mac user!
In the mailbag question Will my computer crash on Y2K if I don’t perform the procedure someone E-mailed to me?, SDSTAFF Ed says
What?? You’re assuming that Microsoft would be ahead of everybody else? For your ed-ification, Ed, I copy the quote below from Apple’s web page. Get a Macintosh and throw your PC (= piece of crap) away.
The good news is that since their introduction in 1984, Macintosh computers have had the ability to make the transition to the year 2000. In fact, the Mac OS and most Mac applications can handle internally generated dates correctly all the way to the year 29,940.
J’ai assez vécu pour voir que différence engendre haine.
Stendhal
Why are they going to crap out in 29940?
Although the Mac OS itself, as well as all Mac-related hardware, is Y2K-compliant, some application software has been found to have minor problems. The Complete Conflict Compendium (http://www.mac-conflicts.com/) discusses this in detail.
Oh, and in answer to beatle’s question: “The original date and time utilities, introduced with the original Macintosh 128K in 1984, used a 32-bit low memory global value to store seconds, starting at 12:00:00 a.m., January 1, 1904. Since the Mac OS used a 32-bit value to store seconds, this means that the last date represented in this 32-bit value is 6:28:15 a.m. on February 6, 2040. The current date and time utilities, documented in Inside Macintosh: Operating System Utilities, use a 64-bit signed value. This covers dates from 30081 B.C. to 29940 A.D.” (Source: Technote 1049, Release 1.0 – © 1996 Apple Computer, Inc.)
All versions of Unix, including Linux and the BSDs, will also be just fine come New Year’s. Unix doesn’t store the date and time in the date/month/year format, but in seconds since a certain arbitrary (but constant) starting point. Now, the amount of space left for the date/time data will eventually fill up - in 2038 - but that does leave programmers a bit of time to deal with the problem.
I believe the Unix community is taking it for granted (not unreasonably) that by 2038 we’ll all be running 64-bit processors.
John W. Kennedy
“Compact is becoming contract; man only earns and pays.”
– Charles Williams
Good God, if we are still using 64-bit processors in 40 years, we are gonna be WAY behind! 
Well, I think 64 bits may be the stopping point for plain-vanilla integer arithmetic for the foreseeable future. (32 has been the norm for over 30 years, and is only just beginning to yield to 64.) The internal paths in the chip are something else again.
John W. Kennedy
“Compact is becoming contract; man only earns and pays.”
– Charles Williams