Sometimes the identity of an anonymous poster is widely known.  Sometimes it's because another commenter exposed it, sometimes because that person inadvertently did so him/herself.  I think GBA's has, in fact, been exposed by both actions.  I know I did so several years ago, I was chastised (and properly so) by the moderators for doing so, I apologized to GBA (under whatever moniker he was using at the time) and have been careful to avoid again exposing his identity.  

At the same time, it would be rather amazing if, hypothetically speaking, someone would write a "letter to the editor" then, using a moniker, praise one's own letter on this site.  IMO, that would be a very tacky thing to do.  

BTW: In response to GBA:   and to paraphrase a HUAC answer:"I am not and have never been a member of the Communist Party."  While I've been called far worse that "komrade"garycrum, it is not my preferred title.