I just read Soma's blog about the Avalon CTP, where he mentioned the microsoft.public.windows.developer.winfx.avalon newsgroup.
With so many channels through which customers can reach a MS employee nowadays, it's easy to forget about good ole' fashioned newsgroups. This is a GoodThing(tm). :) Luckily, Drew and others seem to be on top of things over there. It's great to have a community of folks who love our technology as much as we do.