A guy named Matthew Somerville has created a Google maps mash-up that uses public data from the London government to show the real-time locations of trains in the London Underground system. If you're not in London, this won't be of much practical use, but, as the folks at ReadWriteWeb note, it's still an exciting (if somewhat rough) example of where the internet is going:
As with many real-time technologies, the map shows a very real future for the merging of the real-time Web with the Internet of Things. Soon enough, the objects we interact with on a daily basis - whether trains, planes or our refrigerators - will interact back with us, in real-time.
Now, you may not feel you need a closer relationship with your fridge, but wouldn't it be useful if you could check its contents from your phone, or get an alert when the milk was about to expire?