there are a couple really great books out there about hooves and hoof ailments. Hoof Problems: Hoof Construction, Trimming and Shoeing, Solutions for Common Issues and Ailments - Rob Van Nassau - Hardcover (ISBN 9781570763823) - Buy Books, Music and Movies at Borders
This is one I have and love. Its all about hooves and hoof ailments and proper shoeing techniques.
As far as the debate between barefoot vs shod the major arguing points seem to be what is natural and what isn't. The major thing to remember about shoeing is that every horse is an individual and whats right for some is not right for others.
That being said the major arguments I have heard are about the actual design and carrage of the horses hoof. Horses hooves are designed, as I am sure you are aware, to help absorb shock from the concussion of all that weight hitting a hard surface. As your horse steps down the walls of his hoof actually expand and then contract to help cushion and distribute that blow across the whole sole of the hoof and the frog. When you put a shoe on the hoof it naturally constricts that amount of movement the walls of the hoof have and so it naturally also lessens part of the shock absorbtion. This forces more concussion into the joints and ligaments above the hoof and so causes greater wear and tear on the joints of the horse. HOWEVER, this wear and tear increase in minimal and IF a horse is shod correctly the actual constriction of the movement of the hoof wall is also minimal and 99.9% of horses will have no ill effects from being shod their whole life.
Now that being said horses who are not ridden regulairly, have good strong hoof with no cracks or constricted heels or any of the hundreds of other hoof issues that can arise, or who do not spend a lot of time on hard surfaces such as asphalt on roads don't necessairly need to be shod all the time or at all even. IMO horses who grow good hoof and experience light workouts or lots of pasture time should have their hoofs trimmed regulairly and that's about it (other than regular picking of course.) after all why mess with good hoof if you have it right?
On the other hand if your horse has crappy feet (i.e. Lots of cracks, sensitive to rocks, absesses frequently ect) or if they are riden alot, or on asphalt (as it can wear down the hoof faster and cause tender bare feet) or if you need the traction provided by shoes for your choosen horse sport then by all means shoe your horse and shoe them regularly.
Honestly IMHO the debate of shoes vs no shoes comes down to this "what is best for my horse".
Whatever your choice you need to stick by it. If you want your horses barefoot you have to invest in regular hoof care and make sure that their hooves are shaped and cut properly so you aren't dealing with long toes and chips and cracks all the time. If you shoe your horse do your research, know what your horse needs and ask lots of questions of your farrier. What is he doing to your horses feet? Why is he cutting them at this angle or using that type of shoe? How does your horse grow his hooves? More toe with no heel? Lots of heel and no toe? Does he grow evenly on both feet or does one hoof grow more toe/heel than the other? Your farrier should want to share that information with you and if you can't get a good clear answer out of him/her it may be time to find a new farrier.
Anyways that's just what I know hope it helps!!