On comment spam

Note that I was probably thinking even further; possibly to extend to other aspects than simply the integrity of the identifier [1] - a sort of multi-dimensional trust graph.

Well, maybe I inconsciously try to reach the highest level in the "computer dreamer" metric dimension. More useful dimensions I can think of may be e.g.: kernel programmer, security tester, company X employee, non-spam commenter, etc. The kind of things that social networking sites like to display albeit weakly verified and without user control. A further difficulty is to draw a line between public facts - suitable for certification - and opinions or privacy-related facts - things you must leave out of scope...

[1] Not so simple of course, but still leaves room for improvement: see comment starting by "User Foo is certified but..." on the FAQ page of Advogato.