Well, for a minimalist's version of "implemented". For those that don't take the time to read the referenced thread from the p5p e-mail list. It appears that a patch to implement it has been created but not been accepted to any current or future version of Perl, at least partially because the next version of Perl was in a "feature freeze" at the time.

It is unclear to me whether the patch was fully analyzed nor whether it would have been accepted had there not been a "feature freeze". So whether this will be in a future version of Perl is still in doubt (at least to me).