Photocell on Dash - Auto headlights?

[TravisT]

Just curious, I noticed a photocell-looking thing on the dash almost center of the driver side of my 04 sport. I don't have auto headlights though. Is this just there in the event you had that option, or is that something else altogether?

 

[BlackWorksInc]

Its part of the auto function for your A/C and can be used by a couple other things.