Well, The 6.2.x GitHub repository is kept alive by maintaining compatibility with latest Perl 5 and GHC releases.
As of Pugs 6.28.x, as said in my previous reply, I think while it's attractive as a research project, I'd like to focus on more immediate developments in runtime-agnostic systems (such as Perlito), or on CPAN-interoperable layers (such as MooseX::Declare).
All this can change if Hackage's userbase someday exceeds that of CPAN's, but I don't think it'll happen in the near future, if at all. :-)