In the default .ini file php.ini-dist there is a line that reads as follows:

sendmail_path   =       ;for unix only, may supply arguments as well (default is sendmail -t)

The problem with this line is that it is *not* commented out.  So, when you copy this default file to /usr/local/lib/php.ini and try to use the mail() function, it doesn't work because it's trying to use a sendmail path of "".  Simply putting a semicolon in front of this line causes PHP to go back to using it's default and then things work much better.

Hopefully this makes sense.  This caused me great confusion for awhile.  :-)

Keep up the great work!