It would. I currently use my Gmail contacts for this. Android integration is excellent. iPhone integration is decent. To borrow a term I heard from Mark Suster

It would. I currently use my Gmail contacts for this. Android integration is excellent. iPhone integration is decent. To borrow a term I heard from Mark Suster though, it's a FNAC (feature, not a company). Think about the supply chain, inventory management, retail distribution, OS development and so on that would need to go into this. I simply don't believe the business case for an FB phone exists. What's more, I don't believe FB believes it is either.