A nice feature of running PHP as an interpreted language is the flexibility in variable typing. Variable type in PHP depends on context. You don't get that when you compile a program. Compiled programs require that you define variable types in advance and they can't change.
I would _love_ to see a PHP-to-ILE compiler on the IBM i. That way, we could use PHP as a scripting language for web apps and as a compiled language for batch apps. We could also mix PHP with RPG, COBOL, C, and CL as ILE modules. We could do something like Facebook is doing with PHP and C++ (except we'd be doing it with PHP and ILE).
Dot Foods, Inc.