I've written about a GIS tool called Earthviewer. Jeff Harrison is giving a talk about a group called the Open GIS Consortium, or OGC. OGC is trying to do something similar, but more general and more extensible. They have markup languages for lots of things including geographic data, sensor data, mobile data collection devices, mapping data, and so on. They did a demo last month where they pulled in data from dozens of different data sources all over the world using web services for emergency response. During the project, they actually flew a plane over the area they were interested in and brought in the data live. Pretty cool.
This effort is all being used by the Geospatial One Stop initiative. This kind of capability is vital to first responders like police, fire, and EMTs. In particular, see the Geospatial One Stop Portal Initiative.
I think its interesting to compare this with Earthviewer. In my opinion, Earthviewer has one real advantage vis a vis other GIS tools: their user interface. Is a user interface a competitive advantage? In theory, I'd say "no" since its pretty easy to replicate. In the real world, however, companies do compete on the basis of their user interfaces and others seem to have a tough time getting them right.