iPhone 4 Battery
Nice. Not completely necessary to remove front screen - but be careful if you do it this way...
When replacing the standoff screw closest to the dock connector, make sure it is tightened all the way down. The battery terminal screw fits in the standoff later, and if the standoff isn't tight (NOT TOO TIGHT!) then the battery will not be completely connected and your phone will power off unless tethered. This mimics a bad logic board symptom! Inspect this before replacing your logic board!
I had some trouble getting the mute switch/rocker to function properly, as a couple others have mentioned. There is only one way it will work properly: Make sure the mute rocker is in the muted position with the red dot visible before you re-install the bracket. The switch that you stuck to the bracket by removing the tape backing must also be in the muted position (pushed down toward the back of the case). The tip of the switch fits into a hole in the rocker. If it isn't in the hole, moving the mute rocker will dislodge the taped switch from the bracket. Take your time with this step and make sure the mute rocker feels normal before attaching anything else (phone jack, power button, etc.). Good luck!
Be VERY careful when you are lifting up the drive. Otherwise, you'll need to buy a new hard drive/IR sensory cable! Learn from my fail!