I have used wxWindows sucessfully for a couple of small projects. Very easy to use, works on Gnome, KDE, and Win2K/WinXP. You don't mention the project, so I don't know if it will be good for your situation or not.
Ther is also this on Perl/Tk for your consideration and WishPerl might be worth a look too.
"Nothing is sure but death and taxes" I say combine the two and its death to all taxes!