Taken from the "PHP over Java" aticle on zend.com:
Prominent corporations using PHP include Unilever, Philips, NTT, Cisco, Japan Airlines, Air Canada, Lufthansa, GE Marketplace, Wallstreet😮nline Germany; AuctionWatch, VillageVoice, Dialpad and BMC.
The most current case study (in the same general section) is from a developer working for the US Naval Research Laboratory. Guess what they use for their intranet... yup, PHP.
Zend has just launched a relatively new section on their site called "Why PHP?".... it's linked off the main page (you can't miss it🙂 and should provide you with some ammo in your fight to stay ASP-free. Persumably your bosses will realize that if PHP's good enough for the US Navy and Cisco Inc., it's probably good enough for them🙂 HTH.
geoff