Kind of easy, really. Report RFID tag-seen events almost the same way as done with mobile GPS.
* An application listens to RFID hardware for tag events. App resolves user identity and location
* App publishes data to a middleware
* 2L queries middleware for above data
* 2L displays appropriate visualization of above
Here's a pic of my building's floor plan, CAD drawing superimposed on a GIS shape file, so it's georeferenced:
Then I have this hardware in one of the suites depicted above: