From the Nokia Conversations announcement:
For the system to work, two smartphones will need to have installed the app and there are two very separate parts to the PagSeguro app. You select whether you’re the vendor or the buyer and using the password protection function makes sure you’re ready to transfer or receive the money with the right person.
A vendor types in the amount they are to receive and taps their phone against the buyers. The amount is shown on the buyers screen and it’s here the transaction can be completed, providing you agree, that is.
The money will be withdrawn automatically from a credit card, a PayPal account or from any of the other supported payment types. Payments like this with these phones only works from phone to phone and doesn’t work on existing NFC POS systems.
The PagSeguro NFC app will be available for Brazilian users from May onwards. Here's a (thankfully subtitled) video showing the entire on-screen process from both participants' point of view: