To my knowledge, James Ryan is right in that it means nothing as legality goes.Having said that, I've found that it does tend to have an effect on users.
If the claim is a registered copyright, then the date should be the date claimed in the registration.In cases where the work was substantially revised you may establish a new copyright claim to the revised work by adding another copyright notice with a newer date or by adding an additional date to the existing notice as in "© 2000, 2010".Upcoming posts will discuss “what” and “where,” as well as adding supplementary information in brackets and mixing and matching elements of example references.How do you determine what to do with the date element of your reference list entry?For most references, it’s pretty straightforward: The date element is the year of publication, found on the copyright page (for books) or the first page of the article (for journals); put it in parentheses and follow with a period.
However, as we’ve seen in previous posts, the basic reference pattern can sometimes have a few unexpected twists.
Most sites simply automatically print the current year or their starting year to current year, so it doesn't really help the user determine if the site is maintained or not. I personally think you should be honest to the user about when a page was published/updated.
If the content is a few years old, let the user know.
I tend to stay away from commerce sites that haven't been updated in 5 years :) The copyright notice on a work establishes a claim to copyright.
The date on the notice establishes how far back the claim is made.
Minimize bounce rates by actually updating a site rather than just giving the illusion of maintaining the site.