My main house is at 7100 feet ASL, and I brew all of the time there. My only change is to sometimes brew things a bit longer to offset the lower boiling temperature of water up here. At 7100 (198F), it does not seem to have a large effect if I don't. My cabin, however, is at 10,200 feet ASL and the boiling point of water is only 191F ! That makes a big difference. Otherwise, since the beer is under pressure from CO2 anyways, it doesn't seem to make a huge difference bringing it around once it is kegged. I have noticed, however, that you need longer lines to compensate for the decreased air pressure for serving draft beer at higher altitudes. This includes commercial brews as well. Some of the ski areas never figure this out and must throw 25% of their beer away as foam!
As my logo ( The simple one I have etched on my glasses ) says:
'Beer with Altitude'
Did you have any specific questions I can help you with?