The news in the PHP world today is Facebook\'s HipHop, which:
HipHop for PHP isn\'t technically a compiler itself. Rather it is a source code transformer.
Hip Hop is essentially pointless to everyone except Facebook and other gigantic PHP-based sites. I'm sure many people will jump on the bandwagon due to "it's fast" but how many PHP based apps use whole server farms? Just because you are working on a social network site, doesn't mean you should consider using HH.