Spolsky on Calendars?

A little over a year ago, Joel Spolsky wrote an excellent article entitled The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!). I've been searching the web for something as informative, and readable, on dates, times, calendrical calculations, and related mysteries. If anyone knows of a programmer-oriented tutorial on the subject, please drop me a line (gvwilson at pyre dot you-know-what).