Question: What is the best way to manage GPS coordinates (latitude and longitude) in django models ?
I know that there is a module called GeoDjango but reading the tutorial seems dedicated to GIS and not simply to manage the latitude and longitude.

I do not care to have convenient interface for the admin because int the application I'm creatin the admin is virtually absent. But instead the application will often comunicate with mobile device such as iPhone that,for example, treat coordinates as double (double typedef CLLocationDegrees).

I would simply like an easy way to manage these data in the model?

Answer: 
Algorithms and data structures are the basic tools of a programmer. They are as essential as a hammer (or nail gun) to a house framer. They are the tools that solve problems so you don't have to reinvent the solution.

You should understand what they are, why and how they work, and what their shortcomings are. Knowing this will save you a huge amount of time that could be wasted trying to solve a problem that has a solution.
You can get by programming without being proficient in a particular language, but you cannot program without the knowledge of data structures. Data structures are more of a Computer Science obsession. Each problem will have its own ideal data structure that fits naturally to it and to manipualte the data in the structure you will need algorithms.