A number of websites act as portals to data, software and articles about GIS. These include Directions Magazine, The GeoCommunity, and LBSZone. Some provide original articles, while other focus on press releases.
There are several professional organizations for those involved in geospatial technologies. The Geospatial Information and Technology Association (GITA), The Urban and Regional Information Systems Association (URISA), The American Socity for Photogrammetry and Remote Sensing (ASPRS), The American Congress on Surveying and Mapping (ACSM) tend to be technology organizations. Government focused organizations include the National States Geographic Information Council (NSGIC, for state GIS coordinators), the National Association of Counties (NaCO), The National League of Cities (NLC) and others. Management Association for Private Photogrammetric Surveyors (MAPPS) (MAPPS) and Spatial Technologies Information Association (STIA) are active lobbying bodies for our industry. The Open GIS Consortium is trade association that is leading the development of geoprocessing interoperability computing standards.
There are many print and online publications covering geotechnologies. I started GIS Monitor (free subscription here) four years ago because I felt there was not enough anlaysis of what's going on in the industry.
GITC America, publisher of GIS Monitor also publishes Professional Surveyor and Earth Observation Magazine. I also find interesting original thinking about geotechnologies in Directions Magazine, GeoInformatics, and Geospatial Solutions.
The history of GIS is documented in a few places including a GIS Timeline, and NCGIA's
The GIS History Project. Also worth a look: ESRI timeline.