Essentially, close grip cable rows are hitting your back (the middle). Anything close grip will mainly be targeting the middle of the back. Wider grip exercises will hit the outer parts of the back. Wide Grip Lat Pulldowns will hit the muscle on top of the shoulder blade, the lats, and some but not much at all will hit the middle of the back.
What I am getting at is that it all depends on the width of your grip on how far in on your back it will work the muscle.
If this does not make much sense, I am sorry. Forgive me because I am still fried due to finals and my boss last night after work wanted to finish a tequilla bottle.
Close grip cable rows are very similar to bent over rows concerning the muscles worked. Pullups and pulldowns work the middle and upper back but work the pecs too.
close grip cable rows are a awesome stretch-muscle excercise that supposedly increases the number of IGF-1 receptors. I would do a set of these and a set of pullovers after every back training session.
I actually like to take the one arm attachment and hook it to the top of the cable cross machine and do one arm cable rows, high reps, long stretch. Helps with the arm over arm pull I think...maybe...