Augmented Reality app Layar may not work on the iPhone for a few months to come, but in the meantime try out AR iPhone app World Surfer 2.
Made by San Fran company Geovector, World Surfer 2 is an augmented reality app that, like Layar, lets you point your phone's video camera at the world and see it enhanced by graphics showing points of interest.
In the case of World Surfer, it's about straightforward Yellow Pages-cum-Time Out points of interest: retailers and restaurants etc mashed in with Wikipedia entries for parks and monuments and suchlike.
You can bookmark locations you like - it suggests clean public toilets or text search for stuff nearby which is then shown up in either or "reality view".
A nice feature about this app is that though it works best with the video camera and compass-ennabled iPhone 3Gs, it will also work (sort of) with any iPhone or iPod with the 3.0 operating system.
World Surfer 2 is free on iTunes