Asking around on #perl6 about getting pugs going, I was told it's basically abandonware. ghc has passed it by, and the code in the repository has been known not to build for some time now. No one is working on fixing it or extending it.
Quoting extensively rather than paraphrasing, mostly from diakopter:
also, [...] STD.pm is *the* Perl 6 grammar; Larry's effort is separate from that - his effort is comprised of gimme5/Cursor5, which together produce STD5.pm from STD.pm
Larry Wall, at YAPC, demoed his Perl 6 parser (generated into Perl 5 from STD.pm (Perl 6) by gimme5/Cursor5).
That's src/perl6/*5.* in the pugs source code.
at one point TimToady had a program that would convert STD.pm to a dialect pugs could understand... but nowadays his script
takes it all the way to Perl 5.
Naturally, the denizens suggested other projects:
scrottie: there are actually other attempts... smop/sm0p promises to reignite in early July when ruoso finishes his $project...
also there's the measly parser/interpreter I built and am actively working on
well, there's also elf, which is a very fast implementation on Perl 5
mncharity runs elf
elf is fairly complete, actually... I just can't read the code for the life of me or else I'd help out
scrottie: pmurias and moritz_ help out with elf
scrottie: it doesn't have a homepage, I don't think... the source is in the pugscode svn, like every implementation but rakudo
scrottie: there is also MP6/KP6, which is a (bootstrapped!) implementation in Perl 5... but apparently (I can't substantiate) it
turned out to be quite slow... (probably not nearly as slow as yap6 will be).... fglock built that.
so anyway, in order of activity, it goes rakudo, STD5 (Larry's parser), elf, yap6, smop, kp6, pugs.... but smop will shortly be 2nd/3rd again, I'm sure. in order of completeness, it goes pugs, elf/rakudo (not sure on that order), kp6, smop, yap6
(probably shouldn't be on this list yet)... I'm sure I've left out something somewhere...