Let's see..
using file_get_contents() will pull the exact contents of the file. It will not render that page as php, but print the entire source code.. Consider using Include instead and letting the page print its own output. I believe you can also use include in an if() statement for error reporting - 404s.

Personally, I've not had a need to use include statements yet. Gonna go test that theory out.

Editorial:
I've just played with it.

<?php error_reporting(E_ERROR); if(!isset($_GET['src'])) $src=""index.php";" else $src="$_GET[,­"]; if((include $src) == false){ echo "Source file not found."; } ?>

Include statements must be encapsulated in brackets inside an if() statement. In the case of this, it will include index.php which prints its own output normally, so it displays as part of the page.

file_get_contents is more useful when you are dealing with stored files, such as caches, or doing operations on a binary file.

Personally, I'm not a fan of breaking in and out of php, and prefer to do the entire operation in one go.

If I need to inject a piece of php in the middle of a print, I'd do it like:

print "Ooh, I just rolled a ".rand(1,6)." on my first die, and a ".(rand(0,5)+1)." on my second!";