Damien Seguy has posted the PHP statistics that he's generated for the month of May 2007:
New developments this month include a record growth in PHP5 adoption (up 1.6 percent) with all of the PHP 5.2 versions gaining more users. PHP 5.2 is now topping out as the third most popular version with PHP 4.4.7 dropping consistently and losing more and more users.
New this month : a map of China and USA with detail by province and state. As usual, lots of other details : PHP versions, Apache, country details, etc. Feel free to ask any other details, stats or context about the study.