I posted a comment on a youtube video. The posting process required that I identify myself through a short menu of sites that establish online identities --- Facebook, Yahoo, etc.
We are heading away from anonymity on the internet. To be authoritative and have a voice, you have to be a someone, not a no one.
In special cases the anonymous voice can also have authority. Take my field: information technology. Many technology vendors now offere tech support in the form of a social networking site. Problems get posted by users and solutions are offered either by other users or by posters who are tagged as official experts by the vendor.
In this field, solutions can be tested easily . They either work or they don't. Anonymous posts provide hints or notions of how to solve problems.
Anonymous information, if tested, can be useful.
In his review of James Gleick's new book, "The Information," Geoffrey Nunberg emphasizes the importance of distinguishing the content of the signal from the signal: the number of bits transmitted and received continues to explode, but that does not mean that knowledge is increasing.
As Nunberg points out, "Even Wikipedia’s guidelines insist that articles be based on “reliable, published sources,” a category that excludes most blogs, not to mention Wikipedia itself."
The only reason to read a blog is because you know the author, either in person or from his writing. And the only reason to use Wikipedia for serious research is because most articles have a great bibliography of unique, authoritative voices.
The unique voice has value and authority.