i personally do not like tv's hung over fireplaces. in fact i'd say that about 90% of the tv's i've personally seen hanging on walls in houses are too high on the wall and have you looking up from the sitting position, which i personally hate. when i'm sitting down i want to be looking straight and putting no strain on my neck. and for the most part, fireplaces are somewhat tall so putting a tv above it simply makes it higher than ideal position.
that said if i HAD to put one above a fireplace, i would definitely put it on a tilted wall bracket so that it is angled down towards the seating positions. the ones i have seen above a fireplace typically have somewhere to the left/right that they have the components placed.
are you going to be using a receiver at all? if so this can make wiring wires in wall easier, for the sheer fact you will only really need to run 2 wires through the wall - power cable and hdmi cable to receiver (possibly more if you have different video cables). you could get a long HDMI cable and put the cable box/receiver basically anywhere in the room.
since you asked for some setup pics, here is my setup in my main living room. the wires have since been cleaned up a bit.
it was funny because when i got that tv my wife wanted it hung higher on the wall prior to me doing so and i was explaining to her why higher is stupid, and she was telling me how everyone she's seen is hung higher on the wall, and again i expalined how wrong it is and why it is dumb. so i just did it the right way and now she loves it. that is a 60" tv for reference.
i also have 5 network jacks on the wall behind the stand there so that i have all my components hard wired (except the wii since that needs an adapter for it and wii online sucks).
and since i like to show my theater room that i'm working on, here is that current state. :p