I suspect that Advogato could, eventually, turn out to be the first true weblog software for a focused community.
'Recent diary entries' is, after all, simply a very fast way to read a number of aggregated weblogs without all of that tedious clicking that takes you nowhere much. But without frilly themes and customization, Advogato will never be for the masses.
The trust metric stuff might be a red herring; I can't say that I don't trust e.g. this guy; it would not be possible to explicitly distance him from myself in a graph we were both connected to.
I don't think trust is transitive, commutative, or associative.