Why doesn't my new iPod Touch have a camera?
Apple sells refurbished models of many of their products, including the iPod Touch. So it's quite possible that you have a previous model (also known as the 3rd generation iPod touch). 

To tell, if your iPod Touch looks like this: 



you have the 3rd generation (without the camera).

If it looks like this: 



you have the 4th generation model, with the camera.

If it doesn't look like either of these, you have an even earlier model, but that is unlikely as Apple rarely sells models two generations old. You can see the full range, and get more help on determining the model from this website. Identifying iPod Models