While I know there are plenty of logistical
issues involved, I think
from the point of view of the Foundation's charitable mission this is
somewhat of a problem, because the point of producing Wikipedia is not
just to put up an encyclopedia at *.wikipedia.org, but to produce
encyclopedia articles that are Free and reusable by anyone. If the
articles we distribute are only fully renderable by unreleased software
or software that's particularly complex to set up and configure, that
discourages third-party reuse.
And if that were true, I might agree.
But PHP 5 is neither unreleased nor particularly complex to set up. It's been in
production for years, is widely available on thousands of free and for-pay
hosting services, and can be installed on any home computer or server in a
manner of minutes using any number of package installers.
I was speaking of the use of unreleased versions of MediaWiki and
complex/undocumented extension setups (which extensions *are* enabled on
Wikipedia anyway? I know LaTeX and Cite are; is that all?). PHP 5 is
fine of course.