---- Best way to tell Googlebot a page doesn't exist anymore
tedster - 3:13 pm on Feb 1, 2011 (gmt 0)
This wasn't the first mention of the change, but here, on 2010-04-15 JohnMu does confirm different handling:
If you are certain that the URLs will no longer have content on them, you could also use a 410 HTTP result code, to signal that they are "gone" forever. We may still crawl the URLs (especially when we find new links), but we generally see a 410 HTTP result code as being more permanent than a 404 HTTP result code (which can be transient by definition).