I don't think you need a PHP-backed web server, or even a web server at all, to use the SIMILE timeline. That's the point. It all runs in the browser, and uses a simple file-based structure for the data. You need exactly two files (web page hosting the timeline code and JSON data file). You can keep it on your hard drive or on a public server.
I came across this myself recently, and it was the first time I'd encountered the JSON concept. Pretty cool stuff.