Apparently Mozilla is working on an internal project simply called "Data" where they are proposing to invite the 170 million FireFox users to opt-in to anonymous data collection. Up take would only need to be a small fraction of the 170 million and the worldwide distribution is even more impressive.
One of the first criticisms that everyone will hear is that FireFox users are different from IE, Opera and other users. Thanks to comScore, this difference has already been explored in their Firefox vs. Internet Explorer post. Based on the study findings, a greater proportion of users are male, are more likely to have a household income of over $75,000, and younger than the average internet user.
These known differences are easily accounted for and further, are key demographics that are hard to reach. I would argue this to be a benefit and not a criticism.
Back to what I've been saying for quite some time, web metrics require a lot of heavy lifting, particularly for companies who take the brute force approach. What is interesting and I believe can really change the landscape of web analytics is that this would be the 'other' thing that a company Mozilla can do by leveraging what they already do well. The other analytics companies are reliant on providing some value proposition to users. The problem here is that perceived value changes frequently so keeping value at a minimum level is a constant challenge.
Mozilla has the benefit of already having a great and loyal community and I wouldn't be surprised if the uptake would be quite decent.
So for everyone else in the game, things will only get tougher.