AFAIK there's no module that does this, so I'd just go for parsing the output of lsof; something like:

my @opened_by_X = grep /^X\s+/,split /\n/,`/usr/sbin/lsof`;
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Ofcourse nobody's stopping you from turning this into a module yourself. :-)

Joost.

-- 
#!/usr/bin/perl -np
BEGIN{@ARGV=$0}s(^([^=].*)|=)()s;
=Just another perl hacker\
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