I'm not convinced that these badges would be a good idea. (Note: as of the last data dump, I was first in line to get them.)
Badges have this nasty effect of making people act for the badge rather than for the good of the site. I already see this in the review queue: some reviewers evidently approve blindly (I've seen spam get approved…). I also see this on the edit side: it's happened a few times that a name comes up often under my Reject finger, and after a while I don't see the user editing anything — and I check his profile and find out he made exactly 500 approved edits (most of them mediocre) then stopped.
On the other hand, the suggested edit queue needs more reviewers. (Oh boy, yes, we need help! Please!) I think the most important thing to get more reviewers is a better user interface.
- If you've tried reviewing edits on Stack Overflow and found it a drudgery, try again with Matt's suggested edit extension. You won't be seeing the same edit over and over and over any more.
- Filtering by tags would help, too. (The same thing goes for flags.) Better have some tags with enough eyes and some tags lagging behind than the current state where reviewers have to make uninformed, harried decisions.
That being said, I think we could have two versions of the badge (three is overkill):
- The bronze badge should be a starter badge, for the first time the user reviewed a suggested edit, just to make the user aware of the other side of the coin.
- The silver badge should require more of a time commitment. The number should be higher than 100 (which you can get in less than 10 minutes over 2 days on SO if you click blindly), but not so high that it's out of reach of other sites. 400 would make it enough of a habit on Stack Overflow (you need to spend more than a week) while being achieved by a few people on Super User, Math, Ask Ubuntu, and several other SE2.0 sites (making it less hard to achieve than Generalist).