I started with PERL in 1999, I have used it for a short period of time, and it was my first web-scripting language to produce dynamic web-pages. I was excited about PERL, especially because before this I tried C for the same things. I studied PERL a little bit deeper and my finding was that PERL was just perfect to PROCESS big amount of texts, it has a lot of power for this, and of course web is all about texts, or at least it was in 1999, just a great fit for me. I guess Java, 10 years ago was somehow very difficult for producing web-content, Servlet+JSP, not the best tool I would say.
Using PERL I built an application similar to PHPMyAdmin, I suppose it is still working If I would deploy it on my machine, ... just do not wanna get scared about the code style from the times I was learning PERL.
Today I believe PERL is still one of the best for TEXT PROCESSING and JAVA just can not do these things so fast so great as PERL does.
Everybody knows that Java code compiles to Bytecode which is "executed" by JVM, well PERL is somehow similar, it just does it from one shot, the script is compiled (1st phase), and executed (2nd phase), all at once by the perl.sh (perl.exe)... that's what I know (knew). I did not touch PERL for very long time.
Also, It should still be an option for small-average web-applications, today.
It's good to know it, or at least to know how to start with it, and there is not way to say, that PERL would replace Java, or vice versa, they are both doing their jobs very well today.