The Vibrance adjustment layer in Photoshop is one of those adjustments that you can use without knowing much about it.  Once you apply the adjustment layer, you can play with the two sliders until you get the desired result.  There is a significant difference between the Saturation and Vibrance sliders, although both of them make the colors more saturated.

If you shoot RAW files, you already know that the images come out of the camera pretty flat looking so you have to add saturation and contrast in order to make them look better.  Adding saturation by using the Vibrance adjustment layer is probably the easiest and best approach to color.  Apply the adjustment layer by clicking the icon and move the saturation slider to the right until you get the results you want.  The easiest ways are usually not the best but there is another easy way to do this and make it better.  Instead of using the Saturation slider, at APS we generally always use the Vibrance slider for more pleasing results.The main difference between the Saturation and Vibrance sliders is that the Saturation slider applies even amounts of saturation to all the different colors.  If you slide it all the way to the right most of the colors will be completely blown out (not retaining detail).  However, the Vibrance slider will do the saturation selectively.  What that means is that some colors will get more saturated than others.  Usually the less saturated a color in the photo is, the more effect the vibrance slider will have on it. The vibrance slider is also smartly designed to retain skin color, which is awesome when you are applying it to close up action shots or lifestyles.  It will prevent the skin tones from getting over saturated but it will add color to the colors that are less saturated.
100% Saturation
100% Vibrance So the next time you decide that you want to add a little punch to your images, just use the vibrance slider instead of the saturation slider!