The Sony Xperia S will come pre-loaded with LiveWare Manager, a Sony application that allows you to configure which actions are triggered when specified accessories are connected to the handset. It is LiveWare manager that will enable the configuration of the Sony NFC SmartTags, which are compatible with the Xperia S (and other NFC handsets).
LiveWare manager is not a new application, it has come pre-loaded on the Xperia range for a while and is available to download from the Android market here. At the moment it can be configured to launch actions when headphones, charger or headset are connected. In the screenshots below, you can see an example when connecting a headset. The app will be updated when the Xperia S launches to enable NFC configuration. The Xperia S is due to be here the week commencing March 5th.