A case in point is the ShopSavvy application that allows users to shop for the best on-line price while scanning products in a physical shop. ShopSavvy allows subscribers to perform a purchase on the mobile in real-time. (Read here). According to research done by Coremetrics, almost 10% of on-line purchases now comes from mobile devices in the US. In the same article Amazon reports that mobile on-line purchases have tripled since last year. (Read here).
Of course paying for goods using a mobile device is a bit more tricky. It is not as easy to enter card and CVV numbers standing in an aisle in a shop. Just not practical. So what most on-line app providers do, is allow subscribers to store their payment instrument with them. Payment is then just a "one-tap" instance. With the proliferation of mobile on-line purchasing, this may lead to a situation where you may have registered your credit card details with many different suppliers - some potentially less responsible than others. The complexity when wanting to charge something to an alternative card and the management of payment information sored all over the cloud are just some of the problems that I see.
The challenge is to find a mobile-friendly, easier to use and secure payment solution that can be used across many different applications.