In a new post to his blog, Sandro Groganz asks the questions "does PHP 5 hurt PHP?"
The thing that I keep wondering is if we aren't seeing a slowdown in general PHP adoption due to other technologies being able to get a leg up while PHP 5 was in development and the succeeding slow migration from PHP 4 to 5.
Sandro suggests that, because of the release of PHP5, the creation (and modifications) of PHP applications has slowed, causing the imbalance between applications that are PHP 5 ready.