I think we're starting from the same assumptions - my reference to pedometer meant the software-fused data from whatever on-board inertial/nav sensing was available, 6DOF IMU, compass, etc... In practice in consumer products I most often see this provided as "estimated distance" based on a learned or hard-coded model of what a single step looks like from the IMU (the pedometer part) + the output of GPS/cell/wifi localization.
I'm specifically curious about evidence for a commercial smartphone that can track you to room-level accuracy using only IMU + GPS. (Add in wifi or other RF triangulation and it's clearly a solved problem.) In practice with a cell-phone GPS receiver and IMU only, attached to a person it is a hard problem to track a path to within a few meters. Trying to use accelerometer data to get position information over more than fractions of a second in that situation is... tricky.
This is what Google does, the GPS updates are actually pretty infrequent, especially if you specify low power mode, or they detect a slow activity and or you are indoors.
Google's location API fuses all the sensors, they rely heavily on sensor data for indoor tracking and it's been getting pretty darn good since they've introduced it 2-3 years ago.
I've linked a few google talks in this thread already, and you can read about the Fused Location API.
I'm specifically curious about evidence for a commercial smartphone that can track you to room-level accuracy using only IMU + GPS. (Add in wifi or other RF triangulation and it's clearly a solved problem.) In practice with a cell-phone GPS receiver and IMU only, attached to a person it is a hard problem to track a path to within a few meters. Trying to use accelerometer data to get position information over more than fractions of a second in that situation is... tricky.