A limited edition of the new Samsung Galaxy S III will be used by selected athletes and triallists to make mobile payments at retail locations in London during this summer's Olympics.  The handset will be preloaded with Visa's mobile payment app called Visa payWave.  The recently launched handset is Samsung's official mobile phone for the games. Users select the Visa icon on their handset and hold the device over a contactless terminal to make a payment.  Transactions above £20 require a passcode.