Learning that you have a carpenter ant colony indoors is never pleasant, but then comes the difficult task of locating it.  Carpenter ants do not eat wood, but they will hollow out rotting wood for their colonies.
In homes this usally means wood that has been water damaged, so it is best to start searching around windows, doors, sinks, and other areas prone to water leaks.  However in my case I found a colony in a bit different location.  They were in the attic of my garage and had set up shop in a bundle of cedar shingles we had not gotten around to using yet.  There were already plenty of gaps between the shingles and the wood is very soft. 
I took the following pictures of the colony.  I am not sure why they have the pupae out and exposed, but they are in an undisturbed location.  I did check back a few days later and there were no pupae on top.  I suspect the flash photography caused them to reconsider and move the pupae into more protected areas within the bundle.

The bundle of cedar shingles serving as a carpenter ant hotel.
 

Ants and exposed pupae.
 

Notice the different sizes of the worker ants.

Ants and the sawdust they pile up when excavating a nest.
 

Ants, pupae and sawdust.
 

The gaps between the cedar shingles filled with ants.