Yes and no. Dreamweaver MX merely supports PHP web development. It colors PHP tags in code view, plus it will allow you to quickly throw in predefined PHP variables.
But it will by no means do all of the coding for you. You can make a PHP web site, (or a more complex, forum) but most of the bare bones code you'll have to put in yourself. DWMX can do lots regarding HTML, but the dynamic aspect of it, is mostly your own work.