Geolocation is a factor always more spreading on the web, but what is it?
It consists to geographically reference (geotagging) elements.
To understand this trend here is a list of pratical examples of sites, services and apps that use geolocation:
Dear Map service that allows to create/share own maps/tours
Gowalla, Foursquare, Booyah mobile apps that allows to post/share own position from own smartphone
WordPress Geo Mashup plugin for the famous blogging platform that allows geoblogging (examples here)
Flickr the famous photo hosting service has geotagging features
Browser Geolocation API the geolocation introduced in HTML5
GeoChirp web app that shows tweets from the points you click on map; Twitter includes geolocation features
Geomashable allows Facebook, Twitter, Wikipedia, Bing and Flickr geotagging on iPad
PlaceOpedia allows to connect Wikipedia articles with their geolocations
Geotagged Youtube videos