use of ini vs include file for configuration

I'm curious what the lists' opinions are regarding the use of an .ini file versus an include configuration file in PHP code are? I can see uses for either (or both). To me, it seems that an .ini file would be ideal in the case where you want to allow a simpler interface for people installing your app to configure things that need configuring, and an included PHP code configuration file for things you don't necessarily want the average installer to change. What do you think? Tamara