Twitter for credit card purchases unveiled

Blippy, a service that automatically publishes users' credit card transaction details online, has launched in invitation-only beta.
Users can link a card, as well as accounts at outlets like iTunes and Amazon, to the Blippy site, which then automatically provides a Twitter-style stream of purchases.
The transaction details include the name of the person, how much they spent and where. For Amazon and iTunes purchases it also shows what was bought.
Others can then follow the stream and, as with Twitter, participants can choose to make their purchases private or public.
In an interview with the New York Times, co-founder Philip Kaplan says that as  most people have several credit cards, one of these can be connected to the site as a "social card".
This can then be used to provide friends with information on what you are buying and where you are automatically, without needing to tweet, a concept Kaplan calls "passive sharing".
A feature expected to be added soon will let Blippy automatically update Twitter and Facebook when its users transact.