Somehow, there are some applications in the navigation section available now that weren't there yesterday, but judging by their release date should have been... That App Store is becoming a bigger and bigger miracle to me...
Anyway, there is "Over Here" and the two "Here I Am" which basically all do the same: send your position by email to another iPhone user. Then there is "Path Tracker" which is a tracklogging application.
Tracklogging is a feature that is offered by almost every GPS device. It is nice to know where you have been, for instance if you want to combine your tracklog with fotos of your digital camera (not the iPhones camera, of course).
Unfortunately, PathTracker does not support export (e.g. via GPX files) at this time.
I'd like to cite a funny aspect here. Judge for yourself ;-)
This version 1.0 does not work well on the iPhone 3G. Version 1.1 has big improvements and will hopefully appear in the App Store soon. Please wait for version 1.1 before installing or reviewing this app. The iPhone is so popular that Apple is overwhelmed with application submissions, so please be patient.
The App Store version reads "1.0" at this time.