German Vorwerk shows a carpet with integrated RFID grid.

The smart floor carpet can be used to lead robots around buildings. A floor cleaning robot could clean more efficient as he can use the RFID tags as guides. Data can also be stored to the RFID tags, which could for instance allow areas to be marked as cleaned. Other uses are factory floors where transport robots need to find their way from point A to B.
The Vorwerk RFID smart floor can be installed under almost any floor material. The data communication on 13.56 MHz works up to a 30mm thickness of the floor covering.
German Heise reports that 1m2 of the RFID carpet will be selling for around 15-25 Euros (~$18-30).
More details in this Vorwerk press-release (German).