Nexen.net posted statistics for PHP adoption for september 2006, the results briefly are :
+ PHP 5 awaits PHP 5.2
+ PHP 4.4 is still to outrank PHP 4.3
+ PHP 4.4.2 is the most popular version nowadays
http://community.phpmagazine.net/upload/2006/10/evolution.global.en-thumb.png
Details available for PHP usage on Internet against ASP and others, PHP version distribution, PHP major version distribution, PHP 4/5 middle version distribution, PHP 4.3/4 minor version distribution, PHP 5 minore distribution, PHP adoption by country, PHP 5 adoption by country, PHP Market size by country, Web servers distribution, Apache adoption by country, PHP adoption in Canada, PHP adoption on large domains. In this survey 15 millions servers were surveyed during September 2006, and 8,9 were used for the stats : domaines without web sites, those unreachable, ISP or domain parkings were not considered.