I am working on a public-facing web site which serves up articles for people to read. After some time, articles become stale and we remove them from the site. My question is this: what is the best way to handle the situation when a search engine visits a URL corresponding to a removed article? Should the app respond with a permanent redirect (301 Moved Permanently) to a "article not found" page, or is there a better way to handle this?
Edit
These articles are actually not removed, but they are "unpublished" - and they may return to the "published" state eventually.
You might consider keeping the content up, with some sort of indicator to the person reading it that the content is stale. Then you could also include more relevant content on the page or links to more relevant content.
This might not be appropriate for your situation, or could be more work than its worth, but it may be a good way not to waste potential traffic.
I feel like the 410 Gone response would be the appropriate response, however, you'd basically be telling the search engine "we don't have this content anymore, so stop linking here" - which isn't advantageous to your SEO strategy.