All comments have been positive, it's only fair to add some warnings.

Perl certainly can do everything php can do, and much better for many tasks (especially command line, batch processing, etc.). While it can do UI (Tk), but you don't learn perl to do UI. I think the biggest problem with perl, especially if you're using a shared host, is that it's not supported as much. Most things php are installed by default by most hosting packages, perl is not (I meant mod_perl, perl as command line and CGI usually is). You're right that getting all the package dependencies correctly can be a challenge, sometimes a big challenge, for example, the most popular framework Catalyst takes quite a bit of effort to install, and it's not included in most hosting plans.

I do feel you're in better company using perl, I found perl programmers tend to be better/more versatile programmers than PHP, and Java programmers.