On the PHPClasses.org blog today Manuel Lemos has taken a look at how big the PHP market is - how many developers there are and what kind of tools those developers might be using.
Even knowing that only a fraction of the PHP developers in the world will come to a given PHP event, the more PHP developers there are, greater is the chance to have more developers coming to the event. Therefore the first big question is: how large is the PHP developer community world wide? This is a difficult question. Zend has been publishing rough estimates of the number of PHP developers that exist in the world.
According to some estimates, there's over five million PHP developers out there. The PHPClasses site has this tool that can help show the distribution of some of these in user groups. Manuel also shares some stats he's gathered off of his site - a growing trend for visitors to use Linux and OSX as compared to Windows and the predominance for developers to use Firefox over Internet Explorer.