use in DailyKos
A trusted user on Daily Kos is a user who has a history of posts being highly rated by other users. The term "trusted" thus implies only that the user has achieved a certain credibility with the existing user base - it is not a statement of general trust within the Democratic Party, progressive NGOs, minority groups, or even the current base of users, which includes people who have come in recently.
The main power of a trusted user is that they can apply a "troll rating" to comments, which can eventually cause the comments to disappear. They can also view the hidden comments, in order to restore any that might have been deleted prejudicially, e.g. an ad hominem delete against a hated user, rather than an unworthy specific post. Obviously, this creates a power structure like any other method that reinforces existing users' opinions of each other and gives them power over newer users.
Generally, you become a trusted user by being around for a while, and posting a dozen or so high-rated comments (2 or more recommends) over a period of a week or so, with no low-rated comments. You lose it after a few weeks of inactivity or by getting a comment low-rated. It's not a big deal, so don't fuss over it.
User comments can be rated upwards ("recommended") or downwards ("troll") by other users (only the "trusted" users can issue troll ratings). Having a comment rated upwards grants mojo to the user; having it downrated decreases the user's mojo. Mojo also decays by itself; maintaining a steady mojo level requires posting new high-rated comments every so often. Trusted user status is granted when the user's mojo goes over a certain level. The exact parameters are inside the server software and not generally publicly known. Users' mojo levels are similarly not displayed.
Kept invisible to avoid Slashdot problems
Experience on Slashdot (which uses a system called "karma" similar to mojo) found that displaying karma levels got users obsessed with tending them. This was instrumental in the development of troll culture seeking to demonstrate mastery of the rating system and the power to influence it, by rating worthless posts upwards.
Could be reversible
One suggestion for both mojo and karma is that ratings be reversible so that from a given user's perspective, downgraded comments by someone they personally distrust or disregard are considered upgraded, and upgraded comments are considered downgraded. That is, there would be an option to treat negative karma and negative mojo as being positive, either per user or per the entire service. Some experts have suggested that this equalizes the power between existing users and the new troll point of view. Others however expect it to lead to a situation where new users are encouraged to dissent with the old hands instead of looking for points of agreement.