Dynamic websites are pretty easy in both Perl and PHP, so I don't know if there's any clear winner there. Perl does have several frameworks for making web application development easier, like Catalyst and CGI::Application. As well as sophisticated templating systems like Template. From what I understand, similar things are available in PHP as well, although PHP does not have the breadth of coverage that CPAN does.
in reply to perl vs. php
The main reason I avoid PHP though is the myriad security problems, lack of a consistent database interface, the habit of having a million functions in the main namespace with no particular naming convention or consistency, and the rather strange nature of PHP data types which allow you to mix hashes and ordered lists in a single structure.
I understand PHP is making a lot of progress in these areas, though, so my concerns may be out-of-date.