Who's who in mobile payments

Square faces stiff competition from Google and eBay's PayPal - and Apple and Amazon are circling. Here is a sampling of the players (and a few would-be operators) - and the different parts of the transaction chain they touch.

Card reader? Yes

Wallet? Yes

How wallet works: Touchless

What's in the wallet: All credit/debit

Who takes it? 75,000 mostly small merchants in metropolitan areas

Launch date: 10/2010

@FortuneMagazine - Last updated July 10 2012: 10:51 AM ET
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