[afiori]

for something like this I would feel that the two relevant dates are when the facts happened and when the act of writing is set.

As in if you are writing about a trip in 2002 and the page is written as if you wrote it soon after the trip then the date of publishing is not really essential (in terms of semantic html I think it would still be good etiquette to have is "somewhere" on the page, like in a footer, tagged as such, same thing for a "last updated" date)

In this case I would say that is would be nice as a reader if I can understand what the date mean and if it was backdated or not.