NetBSD‘s Packages Collection aka
pkgsrc now has support for an experimental new framework called “pkgviews”.
This framework, finally allowing multiple versions of one package to co-exist
without conflicts (among other great features), was first proposed by Alistair
Crooks at EuroBSDCon
2002 and has been integrated into pkgsrc by Johnny C. Lam, who just posted
guide to the tech-pkg ml.