Here's an interesting and impacting Google Maps overlay. See the most recent 911 Emergency calls and their specific locations around the city of Seattle, USA.
"In my own opinion": Not since the webcam and perhaps the photo-blog has reality made it's way onto the Internet so quickly. This kind of stuff is what will push portability - PDA's, Smartphones, etc.. Before these services, you could wait. These kinds of services (traffic, taxi locations, emergency situations) will make you want to bring the Internet with you like never before.