This technique is done in photoshop by converting the file to LAB color mode. Find the image tab in the top menu, select mode, then LAB color. It will flatten your image if you have layers open so beware. At this point, I like to duplicate my image layer so I can adjust the opacity of it when I have completed the adjustments. The next step is to open your curves adjustment window. I don't use the curves adjustment layer since I have used it this way in the past. Old habits I guess. Anyway, the first step is to select the "a" channel and move your curves line like shown.
Next step is to move your "b" channel line as shown. You can see how your image is saturating and changing contrast as you adjust your curves.
The last adjustment is to your "lightness" channel. Move the adjustments as this. The top adjustment will bring down the highlights of your photo while the bottom point will lower your contrast. I like to play with the bottom point a little depending on my view for the photo I am working on.
Depending on how you like the color and saturation, you can adjust your opacity to taste. Lastly, you will want to convert your image back to RGB color to make it readable on web and other services. To do this, go to your image menu on the top, select mode, and RGB color. This again will flatten your image if you have made any layers.
That's it! You have completed your LAB color adjustment for your photo. Here is another example of what LAB color can do for a sunset. Click on any of the photos for a large view.