I guess they want to focus on high-quality-posts ,and preventing low-quality post or copied posts trying to cheat ranking-system by any SEO method .
So there are official posts from Matt Cutts, the Google Blog and Search Engine Land .We can trust this information is true ,not a joke .
If you want to know which meta tags Google does pay attention to, see this FAQ. Plus, Googler's JohnMu tweeted that Google also does "not adhere to the "revisit-after" meta tag," if you wanted to know.
Finally, here is a video on Google Blog