The php|architect publishing group has released a new book from Derick Rethans dealing with time/date handling in PHP - php|architect's Guide to Date and Time Programming.
If your development involves working with dates and times, then this book is a must-have. In this book, Derick Rethans (contributor to PHP's core date extension and well-known PHP expert) explores in great detail the subtle nuances of working with dates and times. Frequently PHP developers encounter unexpected results that adversely affect their software and web applications.
The book includes topics like: working with calendars, parsing date/time strings, correctly using the DateTime object and working with dates when you can't get a timestamp. You can find out more on the book's page on the php|architect website.