Introduction
The torn paper-effect is not that well known. In fact, I've only seen it 2 times around the web in logo's and images. It's a tricky technique at first, but once you know the drill, it's really easy.
For this tutorial, again will I be using my logo, because of the simplicity of it. It will be a perfect example.

The Folds
To start, we're gonna grab your object, in my case my logo and start with a simple fold. As you can see I started at the letter C. On a new layer, I grabbed some Black and placed a triagular shape over it. As you can see below, it looks like a part of the C is missing.

Now to make it a little easier to look at, I made the curl orange, because white on white doesn't work. We are gonna make it white later, but for now just look at the shape.
I used the Pen-Tool for this to get the perfect shape. As you can see the shape of the orange curl is the same size as the part we cut away from the C. In theory, it's the same part, just curling around.

On a layer behind it, grab a very small soft brush and start brushing some black behind it. If it's too dark, lower the opacity and go to Filter>Blur>Gaussian Blur to make it a little blurry to fit as a shadow.
Since this is white on white, we don't want it to be that dark - the shadow. When you're done, grab the curl-layer and go to CTRL+U and drag the bottom slider to the right to turn it White!

Continue doing this on a few corners. Do not overdo it. And keep in mind that all folds and curls are different. As you play around with it, keep using the same technique, you can literally mess up the entire image like this. When you have enough, stop there!

Paper-like
Now because I want to simulate the white part of the logo being paper pasted onto the black paper, I want some glue marks. And to do that, I simply lower the opacity on all those black overlay-layers to 90-95.
That way, it looks like there's still some glue left on the black paper.

Now use this fancy paper-texture I got from sxc.hu and place it over your image like so.
CTRL+click the layer of your object, or in this case, the logo and with the selection on, press CTRL+SHIFT+I to invert the selection and press DELETE on the paper-layer.

I just set the layer-style to MULTIPLY since I'm working with black and white here and this will not change anything but the appearence of the white, which we want. As you can see, it now looks like your paper logo is a little torn and folded to pieces!

Conclusion
As I said in the beginning, you can not only use this for logo's, but also for other images like photo's. Try to experiment with larger pagecurls and maybe polaroid photo's? Or normal photo's! With the same technique, you can create some sheets of paper from a notebook. You can also deviate the texture to get lots of different paper-outcomes!
Enjoy!