On the xbox version of Portal 2, I was wondering if there was a way to throw cubes. I believe you can on the computer, but there's nothing about the xbox...
In both PC and console, I believe you can't, the grabbing system has changed since Portal 1, where you could either free or throw (free : grab key, throw : primary fire). Now it's a bit trickier, because you have to make a swing in order to throw your cube. The swing-release is possible because with a mouse, you control the position of the view, which means you can go as fast as you want it to go and instantly release. With a gamepad, however, you control the angular velocity of the view (which is why a mouse FPS player has advantage over a gamepad player : he can just blink his sights on the target, with a negligible travel time, whereas the gamepad user needs the travel time to be accurate in stopping at the right time), which means that you have to trade maximum speed for accuracy. Usually this results in a maximum speed way too low to make a cube throw. Try to boost your view axis sensitivity and see what you can do.
I'm guessing they removed it because you could hack certain puzzles by getting a lucky throw (which was used in many Portal 1 speedruns).
Another reason would be the nature of the grabbing : a Zero Point Energy Field Manipulator like in Half-Life, except without the energy pulse ? Because a ZPEFM + portals would be too much for a single device, but they needed to manipulate stuff without having to code the player hands, and the ZPEFM is a good scenaristic pirouette to justify it.
I hope this helps, if you want a shorter answer, here it is : it is unlikely that you can effectively throw cubes on console, not because of a difference in game code but in the limits of the controller.