How can that pic show a well-designed grid when photoshop only allows 1 color for guides? But if you have the eyes of a designer, you should be able to see the "boxes" among the mess.
Well, Photoshop is not illustrator where you can turn strokes into guides. In PS it's always a mess of guides but if you look carefully, you'll see that the guides actually sets the correct line-heights, padding and margins of the various boxes. I use the Info pallete and snappign to guides and the selection tool to determine widths and ratios. Like content areas will usually be 480px wide or more, sidebars will have 180px or more and also principles like the golden section (1.618:1) can easily be determined with guides and a handy calculator.