Following Steve Jobs' announcement at WWDC07 regarding third parties being able to develop applications for the iPhone with standard Web 2.0 coding, the first, of no doubt very many, has been announced.
Useful, although not particularly exciting (no offence to the developer intended) OneTrip is a web-based shopping list application, and will claim its place in Apple history as the first specially optimised web application to work on the iPhone.
OneTrip is a "single-page, no-reload javascript app" which "is basically a shopping list you can carry around on your iPhone".
As the Applephonegeeks point out, the iPhone isn’t released until June 29th in the America and lordy-only-knows when in Europe, but because OneTrip is a Safari-based web app, you can view it on your computer with the Safari browser and check it out for yourself.
Maybe you could even do a cut-out-and-keep screenprint and stick it on your existing mobile to give yourself a bit of preview (if you're that excited, that is).