The Google Geo Developers Blog has posted an interesting demo of a Google Map and YouTube mash-up that uses the Gears Geolocation API to determine the map user's location.
The Gears Geolocation API provides an approximation (WIFI-based for PC and GPS/CellID-based for mobile devices) of your physical location. The map then uses the YouTube API to load in videos that have been geo-tagged as near your location. It is possible to search for particular tags in the videos geo-tagged near your location. So, for example, it would be possible to load only videos tagged hotels near your current position.
Via: Google Geo Developers Blog