The TIOBE Programming Community Index has chosen PHP as the Programming Language of 2004. The TIOBE Programming Community index gives an indication of the popularity of programming languages.
TIOBE bases its ratings on world-wide availability of skilled engineers, courses and third party vendors. The popular search engines Google, MSN, and Yahoo! are used to calculate the ratings.
As you can see by the information they provide on their site that PHP is still gaining in popularity. One nice thing as well is that they base their stats on the number of lines of code written instead of just how many places PHP is installed.
Note: John Coggeshall has his perspective on this topic.