The typical solution is to cut access holes in the walls and run the cables. In our older home, the walls are wood paneling which has been covered in heavy wallpaper and painted. Not an easy thing to repair without obvious blemishes remaining. A second option is to use the mantel to hide the cables and that is the option I chose. To my amazement, this worked very well.
This instructable will show you how to use a board, a hinge and a magnet to run cables down to the floor (left of fireplace). I also discuss alternatives to accomplish the same thing without using a hinge. Hopefully, this will provide you with some good ideas for your home.
FYI. I love this new 50" Panasonic plasma smart tv. Under $1000 and the picture is fantastic! http://www.amazon.com/gp/product/B00752VKW8/ref=oh_details_o00_s00_i00