While there were major advances (v. 5.2.6 and XML comes to mind), version 5.3 of PHP — available now — is the biggest change for PHP in years!

I'm just adding my voice to the many (thanx, Slashdot!) with the announcement.

From the PHP website:
Some of the key new features include: namespaces, late static binding, closures, optional garbage collection for cyclic references, new extensions (like ext/phar, ext/intl and ext/fileinfo)...

Note how they snuck those slashes in there to advertise the use of 'namespaces" — I'm not in favor of the actual syntax (Flash 4 had slashes for namespaces and not paths but that was an early failure, I would have preferred dot-notation like nearly everywhere else). But here it is!