Mikel Maron’s talk at XTech 2006, GeoRSS : Geographically Encoded Objects for RSS Feeds, is now online. It’s a great introduction to what GeoRSS is, in case you haven’t been following closely. In his talk, Mikel looks at the relative merits of different geospatial markup languages:

There are of course other geodata formats in use, which deserve a look as alternatives to GeoRSS. KML is used in Google Earth, and loads of data layers have been published by an active community. However, KML is very tied to its application, with features specifically aimed for 3D spinny globes, and the spec is controlled by a single organization. GPX, for data interchange between GPS units, is again very tied to specifics of GPS units. GML is a feature rich vocabulary for encoding geographic information, but its complexity has been daunting for unversed developers, and its proper use misunderstood. GML is similar to RDF, defining a number of primitive objects that can be assembled into Profiles for particular purposes. In fact, a GML profile for GeoRSS is a result of the new standard.

[Minor fact check: KML support is native in NASA World Wind, and announced for ESRI ArcGIS Explorer.]

(And if that’s not enough standards, Technorati’s Tantek Çelik has proposed the “geo” microformat, based on the vCard format. [Via Geospatial Semantic Web Blog])

Meanwhile, the latest update to Microsoft’s Virtual Earth supports GeoRSS, and so does Yahoo!’s Maps API. Support for Google Earth is currently available through Zoran Kovacevic’s web app.

I don’t think Google has anything to fear from GeoRSS, precisely because it is so simple and modest, aiming just to georeference web content. KML can do far more, but requires a 3D geobrowser. It would be great if future versions of Google Earth let you subscribe to GeoRSS feeds, just like the better HTML web browsers let you subscribe to RSS. As the competition among virtual globes heats up, this will no doubt become a common feature.