The trust metric seems to have this problem with persistent inflation. Maybe all certifications should decay? That would enable people who were continuous participants in the community to maintain higher ratings than those who drifted in and out rarely.
The problem that I see with this is that it's difficult to make it from "contribution on external project" to "advogato certification", so you'd end up with the opposite problem (masters who hadn't posted in a month would find their certifications dropped to "apprentice" and have to get people to re-certify them first). This implies that we would need reputation management tools integrated with our source control or email tools.
Maybe not such a bad thing, but I'm not sure where to begin.
Update: Perhaps a fealty system is a way to improve the ratios of rankings here. In order to be a master, one must have a certain number of journeymen working with you; ditto with apprentices. That way a ranking can have some additional values associated with it that gives it strength: he is a master vs. he is my master.