I already posted about using Social Graphs (either Facebook or Skype) for making mobile payments and transactions. See my postings "A feature suggestion for Skype: turning skype in a cash-cow machine for mobile payments" and Facebook Social Wallet. The idea is to use Facebook Login (or Skype Login) and transfer Facebook/Skype credits from one account to another in a secure way (see the postings for the details).
Today. Google announced their Wallet based on a chip in your phone where they store the credit card. Technically, I don't quite understand why you need a brand new phone with a special custom chip on it.
Why this should not work with already available mobile phones (e.g. Android, Iphone, Windows mobile, RIM)?
Why do I need to buy a new phone for accessing the Wallet? As described in the postings, I propose to just use either Skype or Facebook. Both of them are already running on all the mobiles available on the markets.