When I was a boy growing up in North West PA I was always excited to find an apple or pear orchard where the farmer used the ancient form of Espalier to grow his fruit trees, I suppose because of the regions vast Concord grape orchards, many farmers also used the same type of post and wire system to grow fruit trees.
Here is a picture of a grape farm from my hometown, the grapes are all grown near Lake Erie. You can see the lake in the background of the picture
Here are a few links on Espalier practices:
http://www.vegetablegardener.com/item/2453/how-to-grow-espalier-apple-trees
http://www.ces.ncsu.edu/depts/hort/hil/hil-619.html
Of course things of beauty come in threes.
Strike that….. Perhaps in fours.
Semper Fi
SAN JACINTO COUNTY OUTLAW 
Bill, am I correct in thinking you can only use the espalier trellising for dwarf or semi dwarf trees?
Queen you know I am not sure, it would make sense….. it is on my bucket list of things I want to do.
You can use the espalier method on any tree. It just takes time to train them via pruning and attaching them to the fixture and some patience.
Its better to start with younger trees, but it can be done with a more mature, but still somewhat smaller stature tree.
Texas A&M has some info on this.
http://aggie-horticulture.tamu.edu/archives/parsons/fruit/fruits.html
http://www.plantanswers.com/pears.htm
Also get in contact with your local county extension agent. they should be able to help or at least point you to someone.
When we lived in AZ there was a Mennonite orchard right next to us and they used the trellising method. It looked like it was easier in some ways, picking, for instance and great for air flow, but it seemed labor intensive to keep the pruning up…but then that’s just part of keeping fruit trees, I guess.
This fall I’m going to plant some apple trees. I’m planting semi dwarfs for the short term and standards for the long haul. Let us know how your’s turn out when you do get around to that project.