At the risk of going off topic, do you really need to run a Perl/Tk (or any other non-browser) GUI for your app ? You might be surprised at what is possible inside the browser these days. E.g., take a quick look at YUI and Ext (among many others). If the issue is interaction with the local desktop, AIR may solve that problem (if one ignores security issues).

Yes, it requires learning Javascript and CSS. But thats probably a good idea/career move anyway.