topo map possibilities on new iphone

Now that the new iphone has a magnetometer to go along with the GPS chip, one thing I haven't seen anyone mention yet are the app possibilities for hikers. Turn-by-turn navigation is now available from AT&T (and TomTom is coming), but that only uses the GPS chip; with the compass feature, there are tremendous possibilities for navigation uses off the beaten path. Plus out in the woods you don't need cell service, as the GPS and magnetometer will work wherever you are. My phone is always with me, and I've always wanted to eventually buy a handheld GPS...it'll be nice to combine it into one very slim, very lightweight device. Hopefully TomTom/Magellan/Garmin etc. are actively working on this for us backpackers.

Well as great as our new phones are (I also have one) they do not have a satellite antenna, they use cell towers to triagulate your position, and I tried mine in the woods no cell signal means no GPS, mine did not work just a few hours from my house due to the very small towne, it will work in parks in the city but the good hiking is always far from cell towers, sorry man, the garmin nuvi phone is supposed to have a full satellite GPS if you need such a thing, I would rather use my garmin vista HCX with 32hrs. on one set of 2600 ma. rechargable batteries.

not true...with an iphone atleast. You're right about the triangulation with cell service, but the gps chip in the iphone will still provide you with a location and use of a gps app.
I live in a rural area myself and have an app that i use (motion x gps) to do my traking, and there are places with no cell service that the gps chip still operates and creates the track. Then when i get home i can upload it to my topousa map!
The iphone apps that I've looked at are still not any better then a handheld gps unit, but is a cheaper way to go if you've already got the phone. Still have an issue with little battery life however.