Via the Professional PHP Blog, there's a few quotes from comments James Gosling, the "father of Java", has made about PHP.

James Gosling, the "father of Java," recently commented on PHP: "PHP and Ruby are perfectly fine systems," he continued, "but they are scripting languages and get their power through specialization: they just generate web pages. But none of them attempt any serious breadth in the application domain and they both have really serious scaling and performance problems."

The headline here should be "Father of Java says writing web applications in PHP is simpler." Both .NET and Java have this be all things to everyone mentality. If you need that generalization, fine, but generalization is not without cost as Gosling points out.

Of course, Gosling defends Java over PHP/Ruby on the basis that they're "just scripting langauges" and not really made for the large-scale, general usage applications. The author also provides some links to articles about Flickr, one of the major PHP success stories.