With the new Accelerated Mobile Pages being launched by Google on the 24th February, there is now questions being asked as to whether AMP is a Ranking Signal. In a recent Google Hangout, John Mueller confirmed that it was not "at the moment."
The question as to whether AMP is a ranking factor has some authority, based on comments made by Google at a Press Event held for the announcement of AMP. While the comments indicating that AMP may become a ranking signal at some point was made informally, it was widely reported at the time.
Fast forward a couple of months to the recent Google Hangout following the launch of AMP, the question was again asked: "Is AMP a ranking signal?". Mueller responded:
At the moment, it is not a ranking signal.
It is obviously one way to make mobile friendly pages, so that might be an option where you do that. I've already seen some websites where they've moved the whole website to the AMP format. Obviously, that is mobile friendly setup, so it kind of picks up the mobile friendly thing.
But just AMP itself is not something that we have a ranking signal at the moment.
The key point in the reply is "At the moment". With more websites implementing AMP (the WordPress AMP plugin has 20,000+ installs) it wouldn't surprise us that once it becomes more widely adopted, it will either become part of the Mobile Friendliness Algorithm or a ranking factor in its own right.
You can view the whole conversation in the Hangout, at 1 5:50 minutes:
You can read our more in-depth discussion about AMP being a ranking factor here.