Note: Ofcourse I know this function is experimental, I'm just trying to help the bugsquiding.

I'm running 4.0.5 and checked the changes in 4.0.6 and 4.0.5 of sockets.c to see if the close function changed, it didn't (as far as I see it), so I think this also applies to 4.0.6

I don't know if this is PPC specific, although I doubt it.

here is the code, that crashes the php module (apache still works, but php doesn't output anything and headers don't get send):
<? close ($fd); ?>
if only crashes after multiple times (and with fast enough subsequent tries ?), this is what I used for testing:
#! /bin/sh
while true
do
  lynx -source http://127.0.0.1/
done
hope this was helpfull