opalORB (a Perl ORB) is an implementation of the OMG CORBA ORB standard and follows the CORBA/e Micro Profile plus DSI/DII. This Perl ORB is written completely in Perl and does not require a Ccompiler, but contains interoperability tests in C++ & Java.
CORBA for PHP is a PHP Extension to use CORBA objects in PHP5(Zend Engine 2). It uses MICO as its ORB and will also provide an Idl-to-PHP language mapping specification and compiler.
For a PHP4 CORBA support look at the great Universe-phpext.