The text to buy service is another thing entirely. Basically it means that any company with an SMS address ie a 7 digit SMS id, can then link a product id with a number and have customers pay for the product immediatly with their cell phones using their Paypal account.
See how this works: You see an add in a magazine for a product you want to buy, the add has an SMS number to call and a product ID, you make the SMS, the seller responds with a confirmation SMS and then Paypal SMS's you for a confirmation of the transaction. Done deal.
This looks like a particularly sweet methodology for smaller items like music and videos. Imagine hearing a song on the radio and at the end a voice says dial 44672 with code 2243. How cool is that!