AmEx lets users tweet to purchase

American Express is enabling customers to sync cards with their Twitter accounts and then make select purchases by tweeting hashtags.

Using its Card Sync technology, AmEx is offering certain cardholders the option to link their plastic to their Twitter account to buy the firm's gift cards and products from Amazon, Sony, Urban Zen and Xbox 360.

To make a purchase, customers tweet special hashtags - which they find by following AmEx's account - and then retweet a confirmation tweet. The product is then automatically shipped to their billing address.