... binary incompatibility between perl5.8.0 and perl5.8.1 ...

Except that as detailed in the release notes (linked above) the ActivePerl release was compiled without the hash randomisation feature enabled - precisely because it would have broken binary compatibility.

I'm sure they'll have a 5.8.2 build out real soon but in the meantime at least the fixes in 5.8.1 are available to the Windows community.