The time to complain (which can be the best contribution of all) is now and, I mean, why not take it to the top?
I disagree. There is no time to complain! A massive amount of people complaining would be the best way to frustrate Larry and all the others that are working hard on Perl6.
Like ysth wrote, it is a mailinglist and not a usenet group. People posting many complaints (instead of adding constructive posts) make the mailinglist utterly useless. So instead of complaining, you could better read all those messages and try to understand the discussions (the first time I'll understand one of those pieces of code, I know I'm not a newbie any longer).
If you want to do more, you could help them, like testing the latest alpha or beta version and reporting what went wrong and maybe even how you thing those errors could be fixed. When you are able to do that, you know that complaining is not the best thing, but that joining them in the development is.
The developers really know that we are all waiting for Perl6 for a lot of years now. Complaining that Perl6 is still not here would not help, really, it would do the opposite. We are not waiting for a depressed Larry, a sad Vladimir Lipsky, a sobbing Dan Sugalski, a screaming Leopold Toetsch nor an offline Luke Palmer. Not to forgot all those other ones that write magically difficult posts, work on utterly wizardlike code, define philosophical concepts.