Is this something that has to be designed from the ground up? How is it in Perl 6?

It has to be considered from the start, at least. Perl 6 has various design decisions that aim at making concurrency as painless as possible, including soft exceptions, contextual instead of global variables, hyper operators and feeds as well as keeping as little mutable state as possible.

However concurrency hasn't been the one and only design goal for Perl 6, so I'm not sure if one can expect the same level of concurrency support as from Erlang. We'll see.