I have created a location-aware Windows Store App that is available as sample source code here. Location Data Logger turns your Windows 8 tablet or ultrabook into a data logger, creating track logs of your position and movement and writing them to your choice of CSV, GPX, and KML files.
In addition to making the source code available, I have started a multi-part blog series that discusses the design and implementation of Location Data Logger, covering everything from high level app and UI design, integration of the geolocation sensor, and a number of Windows 8 runtime features such as suspend and resume, saving applications state, and UI animations.
If you have an interest in developing location-based Windows Store apps, particularly those that use precision location sensors such as GNSS receivers, this is a series you will want to watch. Part 1 came out this morning, and parts 2 and 3 will be out early next week.