2006 Stereo options

[Dcrewchief]

I have a 2006 with standard stereo cd player option. my question is, there is an aux button on the face. does this function actualy work on the stock system? is there a plug on back to access this feature? i i have an iphone 3G which has a built in ipod. i would like to be able to plug it in and listen to it. any help appreciated.
Thanks Don

[OsirisGuy]

I believe the function is useless, unless the aux is in the back.