You know, there are situations where people are actively developing code on legacy hardware, where the old version of Perl is so much better than the alternative (Bourne, or if they're lucky, Korn shell), that they're not very likely to buck the hierarchy to try and compile a Perl on the old stuff. For one, the powers that be might not allow you to put a copy of gcc on a "one of" production box.

Things like Solaris 8 have a default Perl of the 5.005 variety. And yes, they get used for production all the time.