Online Payment at Twitter -- what will they think of next?

Ok, so you get a wildly popular online payment system like PayPal and you link it with equally popular social networking tool-cum-blog Twitter and you get -- (drum rolls) TwitPay. Granted that it has some novelty, but I don't quite see what's the big draw though. Why would people want to sell things over Twitter? There's not much you can say in a 160-character-or-so Twit. You would probably just end up redirecting them to your actual e-commerce site where the real transaction will eventually happen.