Finding the topic of Augmented Reality to be quite fascinating - some of the demos that I've seen on the IPhone have looked phenomenal.
I've been trying to ramp up a bit and pick up some knowledge in the area - some resources that I've come across so far include:
Augmentality - Blog covering augmented reality
Twitaround - demo showing an app on iphone - locating and viewing other twitter users
Nearest Tube - another demo - related to the tube in London
Seen that there's a few books up on Amazon on the topic - considering picking up a couple to get a few more details. Would be interested in any opinions from someone that's already well read in this area.
I can't help but think that a Smarter Planet would include augmented reality - imagining it combined with RFID, intelligent datasources, flexible & service based solutions.