Joab Jackson published an article in National Geographic that give a very basic introduction of GeoRSS and a couple examples of it's use. One of the examples was Where's Tim!!
GeoRSS is a way to add geographic information to an RSS feed. Most generically, it is used to add a latitude / longitude point to an item. To add GeoRSS to your existing feed, add the namespace to your rss element like this:
<rss version="2.0" xmlns:georss="http://www.georss.org/georss" xmlns:gml="http://www.opengis.net/gml">
Then add the lat / long string between your item element tags, like this:
<georss:point>38.1333 -75.674georss:point>
item>
I use GeoRSS on Where's Tim for a couple different things. I generate an RSS feed as my location changes. Each item in the RSS feed represents a place that I was, and each item has a GeoRSS:Point that defines the lat / long point.
I also syndicate the text messages people send me. You can send a message to my phone by clicking the google icon on the map. You then enter an email address (if you want me to respond) and a message and it will go directly to my phone. Using my class that wraps the hostip.info API, I collect location information based on the users IP. I then generate a RSS feed where each item is a text message and I add a GeoRSS:Point if I was able to resolve the user's IP to a city / state.
Fun stuff! For more information, check out the official GeoRSS website.