I just discovered that there is (was?) a proposal for implementing a trust network in Wikipedia.
The proposal originated from a posting of Jimbo Wales himself on a mailing list in February 2004.
Some exerpts from the Wikipedia article follow:

The proposed system has the three key ideas: (1) giving users a formal way of declaring their confidence in other users, (2) a way of seeing which users have declared their trust of a particular user, and (3) the resulting structure of trust-relationships formed between all users.
It provides an additional piece of information that may be useful when coming across another user for the first time. The Wikipedia user base is so large that two well-established and respected editors, concentrating on different areas of Wikipedia, may have no contact between each other for some time. Reading an editor’s user page, browsing through their contributions, and reading the threads in their talk are valuable but time-consuming methods of getting to know someone. Discovering that several reputable users, or users that you have particular regard for, have expressed their trust in an editor is a strong indicator of that editor’s value to Wikipedia. However, the sheer number of editors who trust a user should not be taken as a clear measurement of that user’s trustworthiness: the fact that a user is trusted by dozens of suspected sockpuppets would only harm their reputation.
There are a variety of reasons to express trust in another user: you may have worked together on a proposal or article, reviewed many of their edits in articles on your watchlist, or know them personally. Liking another user should not generally be enough; trusting somebody requires being confident that their contributions are civil, constructive and of generally high quality.

Of course distrust is a tough topic as usual.

Additionally, it would be wise to consider carefully any thoughts of writing explicit statements of distrust, bearing in mind the no personal attacks policy.

It is important to remember that the trust network is not a popularity contest, and so there is no need to actively seek out declarations of trust. The fact that another user has not made a declaration of trust in your favour is by no means a declaration of distrust.

And which trust metric is most suited is tackled as well:

The network itself can be analysed using a trust metric to rate individual users. There are very many different ways to do this, which will produce quite different results, and it is important to note that no metric is endorsed by this proposal.
The simplest trust metric is to count the number of users who trust the rated user, but this system is vulnerable to attack (for instance, the use of sockpuppet accounts to trust oneself).
Another is to count how many links there are in the chain of trust between yourself and another user: if I trust A, who trusts B, who trusts C, and this is the shortest path from myself to C, then C is three links away from me. I might decide that I explicitly trust anybody one link away from me, and implicitly trust anybody up to three links away. This is very different to the previous case: the measurement is personal, not absolute, and will not be affected by sock puppetry.

Since “who trusts you?” is more important than “how many people trust you?” there is little point in creating sock puppets to declare trust in yourself.

The original post of Jimbo is precious as well.

But most would adopt a personal policy of giving mostly positives or abstaining, reserving negatives for worst case scenarios.
Newcomers would have no rating at all, obviously. Very prominent people would have lots of ratings, mostly positive I would have to assume. I would probably have 95% positive rating, but not perfect, since beloved though I am and obviously deserve to be (*wink*), I am a target.
We’d likely see perfect positive ratings for people like Michael Hardy, who keeps his nose to the grindstone editing topics that aren’t controversial, and who stays out of internal politics almost
completely as far as I know.
Some sysops have taken enormous and weighty responsibilities on themselves to do important but controversial work like VfD or banning trolls or mediating disputes or editing articles about the Middle East. We’d naturally expect them to get mixed reviews, but we might be surprised… lots of people would give them positive ratings just for doing those jobs, acknowledging the difficulty and risk involved.

And then Jimbo lists advantages and disadvantages, very interesting!

Well, I’m phauly on Wikipedia, I think you should trust me.