What is the easiest way to activate PHP and MySQL on Mac OS 10.6 (Snow Leopard), 10.7 (Lion), 10.8 (Mountain Lion)?
I'd prefer to use any bundled versions before resorting to downloading from the PHP or MySQL websites. That also rules out MAMP and similar.
I'm comfortable at the command line in Terminal.
Considering it hasn't been released yet, I'm assuming this is a question for ahead-of-time or you have a developer's build. As Benjamin mentioned, MAMP is the easiest way. However, if you want a native install, the process should be like 10.5. PHP comes installed on OS X by default (not always activated for some), just download the 32-bit version of MySQL, start Apache, and you should be good to go. You may have to tweak Apache for PHP or MySQL, depending on what builds are present. I didn't have to tweak anything to have it working.