This room has a big red button that opens the exit door, but the button is guarded by some normal turrets. Furthermore, the big red button is blocked by a giant emancipation grill, so you can't just take a cube straight to the big button.
There is a cube chute with a frankenturret in it. This chute is controlled by an easily accessible small red button. However, when you press it, a catapult below it will knock it into the emancipation grill.
There is a metal walkway near the monitor that is showing Wheatley's face (or glowing eye thingy or whatever). This walkway leads to the big red button.
You have to get a cube up onto the walkway. There is a catapult that will launch you over the walkway.
First, put a portal where the light bridge is shining. Put another portal on the wall near the emancipation grill. Experiment with different locations until the frankencube bounces off of the light bridge when you press the small red button. It will possibly end up in the pit near the normal turrets, so you have to create a portal on the wall down there and another in the main area so you can grab the cube and escape to safety.
Now make the light bridge come out of the wall to the right of the walkway. Pick up the cube and get on the catapult facing the walkway. You and the cube end up on the walkway.
Now make the light bridge come out from a wall in front of the turrets that are guarding the big red button. Walk along the walkway and put the frankencube onto the big red button. Now use portals to get up on the walkway. Go along it and go through the exit door.