On Micropersuasion, there is an interesting post on Geotagging, very good to understand what geotagging is if you're not familiar with it, and you'd like to start discovering its marketing potentials.
To see geotagging in action, I've decided to setup an Adverblog's readers map on Frappr. I'm curious to see where my readers are from (even if Google Analytics is already my best friend for this :-)
If you'd like to post your pin, this is the link to follow: a test for me, and a test for you :-)
Update: don't be shy! Over 55 friends have already shown where they're from!