Don’t know have you heard about Wikitude, but it’s a neat application which uses Wikipedia content in the “augmented reality fashion.” So far it was the “Android thing” only, but now it’s available for the iPhone 3GS users, as well.
Also interesting is that Wikitude — in addition to using the content from Wikipedia — gets local reviews from London-based Qype, and crowdsourced information from its Wikitude.me website. As are result, you can write your own notes and eventually share them with other users…
Enough said. If you own the iPhone 3GS, this is one of those must have apps. Here’s an AppStore link.