Doesn't it have to be software based? You can either develop the hardware, which would be a mobile handset, or the sensors, which would be hardware, or you can develop the software, such as the handset OS, handset apps, or server-side software.

The demonstration they gave at the SHM was an Android app running on a Motorola handset, using the Verizon 3G network, communicating with servers at the E.Digitial office. I think the term platform refers to the combination of mobile app and server.