Where are the [hidden] nibs and other resources?

FROM : James Hober
DATE : Tue Mar 11 18:08:50 2008

In the Finder, when I open up my app's package, I find all my nib 
files and other resources.  If I open the package of an Apple app, 
some nibs and other resources are in there, but many are not.  Where 
are they?  Why aren't they there?  Can I hide my stuff, too?  Should 
I hide my stuff, too?