You can view any waypoint in Google Maps on your iPhone, and you can email locations including latitude, longitude, elevation, and any notes you add to the description. The software also embeds a hyperlink to open Google Maps at the spot you bookmarked. There is also a feature to share saved locations with people on the same wireless network. The usefulness of that feature will depend on how a person wants to use the software.
Waypoints will work on an iPod Touch, but with limited usefulness because there is no on-board GPS in those devices and the WiFi/Skyhook location services aren't really precise enough to take up the slack (nor are hotspots prevalent out in the backcountry).
Read on for more impressions, or check out the screenshot gallery: