My question i had in the past post about how to acces the pipboy while wearing the Power Armor has been answered and confirmed.
Like most people said,the power armor has a hud and the pipboy overlay the hud with text.
The pipboy it's self is not displayed nor it's background monitor but what I can tell the PA arm is displyed in the ground in your face where the pipboy is.
It's pure text on top of your screen from left to right you have tabs to select just like how it shown in your pipboy.
Here's a image that I made roughly how it looks,this is not a leak image.
http://s29.postimg.org/tojwt76ef/ruff_edit.png
Update #1
Your arm is not displayed,only the background enviroment is but blurred.
Also when you bring the display up the screen flickers,it only flickers for that hud and not the PA Hud.
Update #2
The flashlight on the helmet is indeed funcional,you can turn the lights on or off and looks IMHO awesome at night.