Archiving

I notice that a couple of sites, vbulletin.org and digital point specifically, have an archiving system set up and the archives show up in the search results. They seem to be pretty quick at updating - not sure if it's a live archiving or nightly or what.

Is archiving a good thing for SEO? Is this something I should be looking to implement?

If so, what strategies SEO-wise are important?

(can you tell I'm new at this? :) )