Investigate the Media busts the San Francisco Chronicle and their practice of covert censorship:
Suspicious, I then took the following steps: I deleted the "cookies" that SFGate installs on users' computers to identify who they are, then logged out of my account, and then revisited the same thread on my own computer. As I suspected, the comment was no longer visible, replaced by the moderator's notation "This comment has been removed by SFGate." Then when I logged back in to my account, and viewed the thread as "me" again -- the comment was once again visible.Sounds bad enough, but it gets worse. Read the whole thing.
I also confirmed this by viewing the comment thread using a different browser (Firefox) which did not have any SFGate cookies installed yet, and on which I had not logged in to my account. Sure enough, the comment appeared as deleted; while exactly simultaneously, using my original logged-in browser (Safari) the comment was not deleted.
In other words, whenever I viewed the comments thread as "myself" (i.e. logged in under my account name, which in this case was "jimjams"), my comment remained visible; but whenever I viewed the comment thread either anonymously (i.e. not logged in) or from a browser with no SFGate cookies or (most importantly) from some other computer, then my comment was gone -- deleted by the moderators.