Rafael Dohms has posted a review of a book from php|architect - "Date and Time Programming" (Derick Rethans):

A first look at the topic (Date and Time) might get you thinking, "Why the hell do I need a book to teach me about time?" But further investigating, and some life experience will show you that dealing with Date and Time is not always as straightforward as "Its twelve o'clock". Derick's book gives you an in depth look into handling various factors of date and time such as timezones and days that did not exist, as well as finally delivering something missing from php.net: documentation of the DateTime Object.

Rafael mentions some of what the book contains - an introduction to date/time, calendar switches, daylight savings, manipulating date/time values and how the internals of the language uses timezones.