Now, if you're talking about minor errors like misspellings, that seems harmless enough. Catch it soon enough and it's as if you never made the mistake at all. Given the net, though, how easy it would be for government, with the click of a mouse, to transform a former ally, into a historic enemy. Even more problematical, if an error remains online long enough, it takes on a life of its own as it is read, believed, printed out, and used by other reporters in their own stories, as was demonstrated with a number of the more salacious but unverified news items about Clinton and Monica Lewinsky. Wiping those stories from your archive does not relieve you of responsibility for publishing them in the first place.
People act as they do because they have been told certain things are true.
To wipe out the record of what they have been told is to leave people's actions and beliefs inexplicable. For the web publisher, this means there is an obligation to make a public admission of corrections, and to link these in every related story in our archives. Even if all we are doing is deleting content from an archived issue, we should state for the record that it has been removed. For the user of information, the ease of changing content creates an obligation to be skeptical. What we have read one day may not be what is there the next day.