With the announcement of the brand new iPhone 4S, many loyal Apple customers will be opting to upgrade their mobile devices in the near future. If you plan on grabbing an iPhone 4S when it hits the shelves on October 14th, what are you going to do with your 3GS or plain old iPhone 4?

Instead of leaving it in a drawer somewhere or throwing it out, why not recycle it and possibly make a little bit of cash in the process.

That’s Apple cash, mind you.

Many people don’t know that Apple has a “Reuse and Recycle” program for your old Apple devices. With this program, you can send Apple your gently used iPhones, iPads, and Macs, and they might just send you a gift card redeemable at Apple Stores (both retail and online).

Here are the steps to finding out if your device is worth anything:

First, go to the reuse and recycling page to get started. Once there, you’ll be prompted to enter the basic information for your device – for instance a black 32GB iPhone 4.

The next step is to give some more details about your device, whether is still works properly, the battery life, the outside condition, etc.

Apple will then give you an estimate (with the help of electronic recyclers PowerON) for the value of your used device. It could range anywhere from a few bucks to a couple hundred. For example, the functional black 32GB iPhone 4 with minor dings but no significant case damage is estimated to be worth $140. Of course, the estimate is just that – an estimate. The final determination will be made upon actual inspection of the device.

But hey, if you plan on purchasing an iPhone 4S, why not get a little cash from your now-totally-obsolete phone?