Mike Naberezny has posted about the latest release he's made - a 1.0 released too - of the Horde/Yaml library for working with YAML files/information inside of PHP.
This is the package's first stable release. Chuck Hagenbuch started the library as an adaptation of Spyc around six months ago. Since then, he and I have been quietly using and improving it. Along the way, we fixed many issues, added support for pecl/syck, and wrote a test suite with PHPUnit.
You can find the latest download of the package over on the Horde PEAR channel and you can find out more about the YAML (YAML Ain't Markup Language) spec over on the Yaml.org website.