The only advantage that I know of is that Java programmers earn more than phper, though even that is changing.
Seriously, all these platforms like J2EE and .NET had a mainstream respectability that PHP once lacked. Because the big banks and the like used them they were seen as corporate and professional while PHP programmers and users were somehow just back bedroom hackers. All that has changed now and PHP is mainstream, as is Open Source. The quality and sophistication of the products, frameworks and tools available has seen to that. That is why Oracle site now has a PHP link/section as well as NET and Java.
Basically it is the usual swings and roundabouts, but if you google for php vs jsp you'll find some very interesting stuff. Lots of uninformed or biased opinions of course, but try Chris Shiflett's comments for a well informed discussion of the issue.
