If your iPod is running iOS 3.1+, you can use it with iPhiGéNie. Be aware anyway, that there is no GPS on iPod so you'll NOT get your position on maps NOR be able to record tracks. In fact there is sort of localization from phone network relay and wifi spots., but rather imprecise.
Other users on this forum have reported to successfully use external GPS connected to their iPod. IMO this less effective than an iPhone4.
If you have an iPod, try it and see by yourself. If you have none, look to a good offer to get an iPhone from a phone operator.
