Those are all doing the same thing that Corion explained. They are inferring that $$, $undefined_variable etc are symbolic references to an array. If you 'use strict' it will give an error. Without 'use strict' you can do something like: 
perl -e '@hi = (1,2,3), my $x = "hi"; print "@$x\n";'

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and it will output: 
1 2 3

[download]

In reply to Re^3: escaping the @ in an interpolating string by Danny
in thread escaping the @ in an interpolating string by raygun

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