Perl 6 Compilers

Rakudo is based on the Parrot virtual machine. It is developed very actively. Download or compile Rakudo, status.
SMOP is a runtime library to represent Perl 6 objects. It focuses on the meta object programming capabilities. It is actively developed.
Mildew uses STD.pm as a parser and SMOP as runtime. It is actively developed.
Sprixel uses JavaScript to execute abstract syntax trees generated by STD.pm. It is actively developed.
Elf is a bootstrapped compiler with Perl 5 and Lisp backends. Only very little activity since March 2009.
Pugs is written in Haskell, and has been inactive since mid 2007.

Blizkost is a Perl 5 bridge for Parrot, making Perl 5 code available from Rakudo and other parrot-based compilers.
Rakudo's setting library
SMOP's setting library
Elf's setting library (lisp)