Resources nodes in a zone will always spawn the same tier of item, but in the case of ore, it won't always be the same type. Also, only a fraction of the total nodes in a zone will be active at any given time.
I've been playing with a plugin to record the locations of resources, but with the current API, I'm not happy with its functionality. All locations have to be entered manually (I really wish scripts could get the current location) and there is no nice way to display these locations on a map. I've tried using a screen capture to create an editable map, but it won't scale to different screen sizes.