Talk on Web 2.0 mapping technologies plus comparison with GIS technology. The link at the end goes to a Google Earth demonstration found on my blog.
http://gisatvassar.blogspot.com/2007/10/google-earth-lunchtime-demonstration.html
8. Spatial accuracy and precision From OgleEarth blogger: There is no stated accuracy, and accuracy varies. … Of course, Google Earth is free, and good enough for most uses, and especially in the US and Europe the accuracy is high and errors negligible (< 4m)… From a Google Earth contact: Check out this Wikipedia page: http://en.wikipedia.org/wiki/Google_Earth#Resolution_and_accuracy