Virtual ISP Ltd supports PHP and is running 4.0.1pl2 at present with GD, MySQL, TTF precompiled. They run it as an apache service and most of their core apps are written in PHP both front end and back-end processing.
http://www.virtualisp.co.uk or e-mail: support@virtualisp.co.uk.
I have my site there which although there's not much on it, I use it to test allsorts of ideas for my clients before integrating code into their own sites.
Hope this helps.
Regards
James