If you are scratching your head over where they stuck the php.ini file in MAMP 2 (both Pro and regular), wonder no more! Doing a quick spotlight search reveals the php.ini file is in one of two locations (based on the version of PHP you are running):
/Applications/MAMP/bin/php/php5.2.17/conf/php.ini
- or -
/Applications/MAMP/bin/php/php5.3.6/conf/php.ini
Hope this helps anyone who has been stuck looking for the file (as I was). Configure away!