I swear I've written on this topic recently, but all I can find is this node about Tk::HTML.

Other browsers in Perl:
artemis: this is a total hack job, and the lunatic that started the project can never seem to keep make progress. I'm guessing there's a major rewrite and some architectural rethinking in Artemis' near future. (If the author manages to pay any attention to his projects, that is, he's a real slouch in that regard.)

Whole book on the topic of web client programming online at O'Reilly.

A WML browser: not quite HTML, but might offer some architectural ideas.

Of course tkweb is included with Tk::HTML. Farther along than some stuff I've seen, but I think it has a ways to go. Table-based sites like PM don't render at all.

And I have a project that I found one day on the web, that I can't find a link to. Note to developers: always put at least your name on a script, and maybe a link or an email address.

But the real question: what can a Perl browser offer than one written in C (Mozilla) and one written in C++ (Konqueror) can't? Both the Mozilla and Konqueror browsers are based on rendering engines that are theoretically separable from much of the other software included in a browser (AFAIK), so it might be better to build bindings that could link Perl to those rendering engines, or to work on Perl scripted plug-ins.

Different people have very different ideas about what web browsers are and how they should behave. On the one hand a browser has to render every pixel exactly as the designer intended, even though many web designers are incredibly sloppy about the way they build pages, so that clients have to guess what they meant to do. On the other hand, some people think a browser that displays the text mostly correctly is sufficient-- they won't use sites that don't conform well enough to the standard to allow for that.

And in the end, a Perl browser comes down to a question of making choices. You could do everything, but you'd need a super-computer to run it on, Perl trying to emulate IE6 would run slooooow on a normal home computer. OTOH, a Perl browser that targeted a specific application would make a lot of sense. And it might help to think of it as an HTTP/HTML client more than a "browser". That way you're freer to think outside the norm.

I think Tk::HTML and tkweb show the most promise, and would recommend looking at ways to help push those forward, or merge the two-- since tkweb does not use Tk::HTML but Tk::Text (which is a very versatile widget in the first place).