With some googling I've found some additional evidence that Perl 6 indeed has no GIL:
As the creator of Perl himself stated in an interview:
[...] For developers who are already sophisticated, they'll see that most of the problems endemic to the currently available dynamic languages are solved in Perl 6. We understand lexical and dynamic scoping. We detect most typos at compile time. We don't have a global interpreter lock.
Source: Perl creator Larry Wall: Rethought version 6 due this year
Some more evidence:
I don't know why, but the addition of Perl 6 to the Wikipedia article was done two weeks ago and maybe it needs to be reverted.