I think with the emergence of .NET, PHP, J2EE, Python etc, Perl may have lost its niche a bit as a popular programming language. The buzz is all around PHP these days and also around Python.
I agree with what has been mentioned above, the emergence of .NET, PHP and Python has led to downfall of Perl. I think Perl is fading as a web language because people tend to use what is easier and more productive.