WWW::Shorten::Digg is now on CPAN.
I wrote a Digg URL shortening module in Perl. You will have to wait at most 3 weeks for me to get a PAUSE ID before you can download it from CPAN. Mail me if you like to use it now. You can see the result of the module on http://twitter.com/volkskrant. According to Matthew Hurst Digg is not used on Twitter yet. My module will change that 😉