Our friends at Tricycle will push through a zero-based karma system (no self-voting possible) sometime this evening. At present this will only cover future posts/comments - they may go back and revise history some time in the indefinite future (or not), but apparently that would be overly complicated for now. We'll see how this works.
Great. I really hope that, when time permits, the folks at Tricycle can apply this retroactively as well. There are a few users who, despite posting comments of low quality, manage to have high karmas due to sheer frequency of commenting.
I don't see why it would be at all complicated to do. Shouldn't it just be something like
UPDATE comments c SET c.score = c.score - 1 WHERE c.post_date < 'some time today'
UPDATE users u SET u.karma = u.karma - (SELECT COUNT(*) FROM comments c WHERE c.author = u.id AND c.post_date < 'some time today')?