First, thanks for writing the module!  As to the name, I think Unix::Lsof is fine — if anyone wants to reimplement it in pure Perl, they could still name it Unix::Lsof::Perl (which would be in line with the naming convention used with Net::SSH::Perl).

I have no definitive opinion regarding 2. and 3. (IOW, it's fine with me as you have it :), but I would personally rather avoid spaces in hash keys (4.).

Running make test on my Debian box (etch, i.e. lsof 4.77) with Perl 5.8.8 gives:

$ make test
PERL_DL_NONLAZY=1 /usr/bin/perl "-MExtUtils::Command::MM" "-e" "test_h
+arness(0, 'blib/lib', 'blib/arch')" t/*.t
t/10.procedural.....ok                                                
+       
        5/12 skipped: Test::Exception not installed
t/20.lsof-result....ok 1/50                                           
+       
#   Failed test 'returns true if the file exists'
#   in t/20.lsof-result.t at line 27.

#   Failed test 'Reports no errors when there aren't any'
#   in t/20.lsof-result.t at line 28.
t/20.lsof-result....NOK 11                                            
+       
#   Failed test 'returns true if the file is open'
#   in t/20.lsof-result.t at line 34.
t/20.lsof-result....NOK 12                                            
+       
#   Failed test 'returns true when called on process'
#   in t/20.lsof-result.t at line 37.
t/20.lsof-result....NOK 14# Looks like you failed 4 tests of 50.      
+       
t/20.lsof-result....dubious                                           
+       
        Test returned status 4 (wstat 1024, 0x400)
DIED. FAILED tests 10-12, 14
        Failed 4/50 tests, 92.00% okay (less 1 skipped test: 45 okay, 
+90.00%)
t/pod-coverage......skipped
        all skipped: Test::Pod::Coverage 1.04 required for testing POD
+ coverage
t/pod...............skipped
        all skipped: Test::Pod 1.14 required for testing POD
Failed Test        Stat Wstat Total Fail  Failed  List of Failed
----------------------------------------------------------------------
+---------
t/20.lsof-result.t    4  1024    50    4   8.00%  10-12 14
2 tests and 6 subtests skipped.
Failed 1/4 test scripts, 75.00% okay. 4/62 subtests failed, 93.55% oka
+y.
make: *** [test_dynamic] Error 255
[download]

I'd be happy to provide more info (should you want it) to resolve the remaining issues... Feel free to /msg me.