Nessa has two posts that talk about how to use PHP to display the versions of software running on the local machine.

I've been working on this application for work that does some simple server reporting, part of which involves displaying the versions of major software running on the machines. [...] I need to be aware of this to make sure that customers are being moved to servers with compatible versions. It's also good in tracking and planning upgrades.

In the first post she recommends using the exec function in PHP to run system commands to get things like the cpanel version, python version and what perl you have installed.

Part two shows a little bit different way to get some of the same information - using the data in the /proc/version file as a single resource to get OS information.