At last count, I think there are around 7 or 8 iphone applications you can use for GPS logging. I have not tried them all, but I did give TrailGuru a try. I tested TrailGuru on the ebike on a short ride to the grocery.
Like Path Tracker (reviewed here) the iPhone takes a GPS samples and holds them in it is memory (or uploads depending on the connection) and stores you data online as a path. You can also download GPX data for your own analysis. What is different here, and I think interesting, is the idea of creating a community around your paths.
Each ride is recorded and logged in such a way that others doing a similar ride, or looking for a ride in the same area, can access and look at routes others have taken including elevation maps, photos and notes from those rides. There is also the ability to download the raw GPX data as with Path Tracker. My main complaint with TrailGuru is the inability to display data in Imperial units (miles). I’m sure that will be addressed soon.