The Big Date and Time Debacle

I am having great difficulty understanding dates and times with PHP and MySql. As far as I understand them, the PHP date and time construct is timezone and DST aware, but MySql's DATETIME and TIMESTAMP fields are not. I believe that this is where my confusion originates from. After searching the web and the docs for hours, I have not managed to find an article that explains how this system works and what the best practices are for an application that may be used in many timezones, some with DST and some without. Please point me in the direction of a good source on this subject. I am new to PHP, coming from a several-year-long period of C++ and, recently, ASP.NET. (Ok, I admit it, I only started using PHP a week ago!) BTW: I've loved every minute of it! PHP Rocks!