I just published the second part of the serie about PHP configurations. This part focuses on three aspects of PHP: PHP extensions, PHP streams, and disabled functions.
You can find the statistics themselves here and the latest configuration statistics here. It's interesting to see the drop-off when it comes to the various modules that are installed ("php, ftp and http are the most common. Besides them, tough luck.") and to see the somewhat more gradual curve of which functions are disabled - with system() topping out the list (with good reason).