It has been a really long time since I last wrote anything about it - but I had the chance to work on my Kerberos PHP extension earlier this year. There have been some API changes and one big new feature: It now contains bindings for GSSAPI functions which might be really useful for people implementing kerberized protocols in PHP. Also API documentation is now included and credential cache management has been changed to better work in web environments.
Feel free to test and use the new version which can be downloaded here:
php_krb5-1.0rc1.tar.bz2 