GPSLog Labs works quite well on the iPhone, but it's not a truly useful mobile experience:

So, I've added a mobile version of the site:

It will take advantage of the GPS in the phone (if available) to show you information in GPSLog Labs that's relevant to your current location (if it can recognise it) and you can also add new places into GPSLog Labs directly from the phone while you're at the place. Meaning logs you upload later will be automatically chopped without you having to edit them.

You can quickly browse through the logs you've uploaded, view their stats, maps and graphs:

This is just the beginning, expect a lot more useful features soon (and let me know if you've got any ideas too!)