Google Wallet pin code can be cracked in as little as 18 minutes
pcmag.com
pcmag.com
You have to have the phone (something I would notice was missing immediately, unlike my CC which I would notice next time I bought something) and you have to have a pin (which can be cracked relatively quickly, assuming it doesn't delay between attempts or lock after a few failures). That's 2-factor identification.
If there's also a requirement for photo ID, that's almost as good as 3-factor. (Technically, 2 of these are 'something you have', but the photo helps push 1 towards 'something you are'.)