A GPS chip, which is a part of the 3G cellular radio, is necessary to use some features of iHikeGPS.
Other features such as viewing the topo maps can be done on devices without a GPS chip.
The original iPhone and the first generation iPod touch are not supported.

Device	Download and View USA Maps	View and Email Current Location	Record and Email Tracks	Create and Email Waypoints
iPhone 3GS	Yes	Yes	Yes	Yes
iPhone 3G	Yes	Yes	Yes	Yes
Original iPhone	No	No	No	No
iPad with 3G	Yes	Yes	Yes	Yes
iPad WiFi	Yes	No	No	Yes
iPod touch (3rd Generation)	Yes	No	No	Yes
iPod touch (2nd Generation)	Yes	No	No	Yes
iPod touch (1st Generation)	No	No	No	No