Similar effects can be achieved using noise or even manually creating the light and dark tones with brushes etc and then blurring them into the "brushed metal" effect.
Anyway, let me explain how I achieve this particular effect.
Create your new canvas, for the sake of this tutorial I am using a 600 by 600 pixel square, 72 PPI and a transparent background.
Go to Filter > Render > Clouds
We are going to boost the contrast of the cloud effect, rather than using the brightness/contrast tool we can get a more dramatic and customisable effect using the levels tool.
Go to Image > Adjustments > Levels
(Keyboard shortcut (Windows) Ctrl + L)
Now drag the right point left and the left point right.
This is a quick succession of 3 actions.
Firstly duplicate the layer, you can achieve this by dragging the current layer to the new layer button on the layers pallet.
Now change the blending mode to overlay.
Lastly rotate the new layer 180 degrees.
Go to Edit > Transform > Rotate 180 degrees
(Keyboard shortcut (Windows) Ctrl + T and manually rotate the layer)
Now comes the part where you can see some real results as the image comes together.
We are going to apply a motion blur.
First, we need to merge the two layers together, you can do this by pressing Ctrl + E on the keyboard or right clicking the top layer and selecting merge down.
To do this go to Filter > Blur > Motion Blur.
Ive used the settings -45 degrees and distance of 600.
As you can see, for all intent and purpose the metal effect is coming together, I hope you would agree.
Now we are going to add the last effect, to try and bring a little more shine and realism to the piece.
Go to Layer Styles and select Gradient Overlay.
Change the gradient pallet to metals.
Lastly have a play with the settings to achieve your desired shine. I have used silver bars, 45 degrees and 50% opacity.
This is my final image.
And with a few extra details added, it really comes alive:
This is just scratching the surface of what can be achieved, if you are going for super realism, you may want to work on the detailing however this effect works really well on web interfaces, signatures, avatars and other web based graphics.
Here is an example of it in practical use.
I would love to see examples of you using this effect and the results of you following this tutorial.
If you want or need help with any part of this tutorial, please keep questions confined to this thread and do not email or PM me, let others learn from your questions.