Absolutely agree with the need for credit. This is a fundamental of getting anyone to do anything, and is at the root of the many cultural problems in modern research. What I find interesting is that credit can seem trivial, people work hard to get high kudos on Stack Overflow or to get Facebook/Friendfeed "likes" or retweets. As these become important to people they can start to become "real" (Stack Overflow scores have appeared on some CVs for instance). To some extent I see these high profile examples of community review as starting to provide some legitimacy for those kind of contributions precisely because they have a high profile.

In terms of the "technical quality of review" question. I've certainly heard (but can't lay my hands on any examples at the moment) CNS staff and editors say things like "the most rigorous peer review", "always send to reviewers at least twice for detailed comments", "often request extra experiments". Again this is partly confusion over what peer review does and what its for but the brands of CNS are bound up with the idea that quality and stringency of review is higher here.

But at some level I'd also invoke the "extraordinary claims require extraordinary evidence" rule. The examples I gave all made extraordinary claims. If peer review is going to do anything useful it must surely subject such claims to heavy duty scrutiny? I'm sure for every bad example exposed in a high profile journal there are many lower profile examples that never get picked up of course.