Information needed to evaluate PHP (scalability, high end features, etc.)

Just realized that I sent this to the PHP3 list when it probably was most appropriate here :-) I assume parts of this have been address previously but I need information more information, I have pretty much decided that PHP is the right choice for some of our development however I need more information to convince myself and my collegues. Currently we are evaluating PHP 4 beta 2 so please try to base answer on that if possible. How well does PHP scale to large tasks? By large I mean running on 5 or more load balanced servers handling millions of requests and large data transfers each day. I would also like to know if anyone has any success stories with php under fhttpd and the use of a non-forking select() based server makes a significant performance increase. Is there a way that PHP can be called from perl or another language and pass variables between the two with minimal overhead? Can a PHP interpreter by embedded like perl can be..a few quick calls from C and linking the correct libs? Are there any known limitations to the loads that PHP can handle or workarounds people have come across? Thanks in advance for you help. I have used PHP and find it to be an excellent platform I just have some of the concerns listed above before employing it in a massive production environment. Thanks, Paul Dlug