Twitter founder working on an add-on device for the iPhone that will provide the ability to swipe and process credit cards & payments.

"Almost immediately following Twitter coming back from a planned downtime this afternoon, co-founder and current Chairman Jack Dorsey sent out a tweet letting his followers know that he was, “Getting ready to embark on something new and entirely different. Excited!” Dorsey is getting ready to launch his next startup, he’s confirmed to us."

"It’s a service that allows anyone with an iPhone to become a merchant. Just like the wireless credit card swipers you see at certain shops and restaurants, you can carry around your iPhone and take payments."