Rich Ersek has created a new Atlas blog for official announcements about Atlas, at http://weblogs.asp.net/atlas. We'll be using this blog to announce updates to the Atlas site at http://atlas.asp.net, including updated preview bits, new samples and quickstarts, and articles. We're going to be updating the PDC preview bits with bug fixes in the next few days, and then make new releases available every month or so.
If you want to keep track of what's happening with Atlas, please subscribe to the RSS feed for the Atlas Blog.