Greg Beaver has a new post today with mentions of a few things, but mainly the work that he's done to create a parser generator in PHP.
About three weeks ago, I looked at the state of the parser generator world out there for PHP, and it is pretty dismal. Antlr3 will theoretically support PHP 5 generation, but it's impossible to find any source in spite of several fruitless hours of googling.
I finally decided that if this is ever going to happen, I'll have to get off my butt and do it. So, two weeks ago, I grabbed the source of the Lemon parser generator from its website
He follows the path he took, using the code from the Lemon parser, translating it into a PHP version, and correcting a few bugs along the way.
In the process, I have a fully working PGN file parser that will make its way into a PEAR proposal as soon as I get around to integrating it with Games_Chess to do full validation of the contents of the PGN file. However, the parser works 100% even with some of the weirdest PGN things I could throw at it.
Sebastian Bergmann also comments in his blog about the work Greg's done.