I was asked about PHP going with Zend Server, specifically from which sources it is built – as we don’t ship source packages for the builds. Since Zend Server includes PHP build that can have some patches applied from SVN past the release (i.e. if the package has version 5.2.10 it might have some patches that were in SVN 5.2 branch past 5.2.10 tag) – I think it is important that people know what they are going to run if the use Zend Server.
So, there is some solution for that – we do have packages with PHP sources called php-5.2-source-zend-server and php-5.3-source-zend-server. If you are using RPM/DEB setup for Zend Server, you can just install these packages by name and get it in /usr/local/zend/share/php-source/ and if you install it any other way (or just curious?) I guess you could take packages directly from RPM or DEB repo and install them manually :) Those are exactly the sources from which the binaries are built.
What we don’t have yet is a changelog that describes in detail which patches are going into that release additionally to pure X.Y.Z tag. I’ve asked Powers That Be to add it, so hopefully it’d happen soon too.
P.S. If you need help on how to add custom extension to ZS, we have DevZone article about it.