Google Nexus S is the first Android phone to include NFC (Near-field communication) for wireless hardware for applications such as contactless payment and perhaps proximity based target advertising.
I wonder if the micro SD card slot on other Android phones supports the SD IO standard. The SD card interface also defines an interface for devices as well as storage cards, for example a SD sized WiFi transmitter could be fitted to photo cameras for transmitting pictures to the internet as they were taken.
I wonder if the micro SD card slot also has this capability and if the NFC chip and antenna could be viable in such a form factor (and for some phones underneath the battery, but still user removable)?