I'm failing to see how this differs from http://www.cacert.org/, though perhaps this would be more strict on participation?
CAcert's goal is to issue certificates for free, by implementing an alternate identity validation model. The SSL co-op's goal is to issue a subset of certificates for free, by having those who take advantage of that service share in the costs of running the infrastructure required to do so.
CAcert's determination to stick to its guns on doing everything "on the cheap" is admirable, and I'd quite honestly much prefer it if they succeeded (it'd be a lot less work for me, for one thing). However, looking at the browser inclusion landscape as it currently exists, I have doubts that CAcert has much hope of ever being widely accepted in the browsers. Worse, you can only change the rules about inclusion if you're already in the club... it's a nasty chicken-and-egg problem.