Pseudonyms prevent texts from being impersonal, from pretending to objectivity; they draw attention to the author's role in a way that a straight author does not. At the same time, though, pseudonyms make a text more fully public: by hiding the author's identity, the author becomes potentially anyone. Pseudonyms mean something, and one of the things they mean is that the pseudonymous writer has a reason for pseudonymity. When pseudonymity becomes a generic feature, as with essay periodicals and blogs, one of the things that means is that the genre entails risk, that publishing is risky.
(from The Long 18th.)
The essay is great to read, I have to say, even though it's probably almost a year old. tychoish brings a whole new meaning to the term "late breaking," alas. The particular quote about the role of pseudonyms, is I think really great, and I hope to be able to quote/refrence it again in the future.