Well, few years back Google went and bought out the Usenet archives from Deja, and have combined the Usenet newsgroups with their Google Groups**. We also have Yahoo! Groups, which as far as I know bears no relation to the original Usenet.
Here are the GIS-related Usenet, Google Groups, and Yahoo! Groups that I monitor. Monitoring is actually quite easy as Google and Yahoo! provide RSS for open/public groups (those not requiring registration). Mind you, this is not even close to a comprehensive list...Only those I monitor.
- Usenet Groups
- comp.infosystems.gis [feed]
- comp.soft-sys.gis.esri [feed]
- sci.geo.cartography [feed]
- ArcGIS Google Group [feed]
- ESRI Google Group [feed]
- GIS Educators Google Group [feed]
- Google Maps API Google Group [feed]
- Professional GIS / GPS Developers Google Group [feed]
- gisindia at Yahoo! Groups [feed]
- new_ai_geostats at Yahoo! Groups [feed]