Seeing if a point is in a defined area

So I need to find a solution for finding out if a person is in a distributors area or not. Is this something that takes place in SQL (MySQL) or CF? Is there something that has already been built that someone gave away?

I’ve found that the google maps has an api that allows me to do this, but unfortunately it’s all client based…*WHICH I’ve thought I could callout to the page and register the response via a form that submits, but that’s sounds so lame.

Anywho… thanks for any points of direction or tips.*