hard to say how you'd go about it exactly, something like that is more stumbled upon. I'd start by selecting 2 colors (fore and back) and rendering clouds (filters>render>clouds) then proceeding with other filters to distort it further. brightness/contrast etc can also be useful. I'm not certain if there's a "recipe" for creating that exact effect, but with experimentation you may be able to approximate it, or create something you like as much or more. hope that helps.

You could try Kai's Power Tools #3 - Texture Explorer. It has some presets that are similar, and you could try tweaking the colors, density, etc.

I might have something similar - I'm sure you can get the rest with additional filters or selection.

Filter > Render > Clouds
Filter > Pixelate > Crystalize (about 45)
Filter > Stylize > Glowing Edges (width = 3, brightness = 7, smoothness = 8)
Filter > Distort > Ocean Ripple (size = 1, magnitude = 3)
Image > Adjust > Levels (enough to bring up some highlights and midtones)
Select > Color range (pick the black as your background color, add the darkest strands, and raise up the Fuzziness to about 75)
Filter > Blur > Gaussian (radius = 2.0 pixels)

to get the depth effect and the harder edges try applying paint daubs or fresco. than mess around with the curves or saturation. otherwise im stumped

Wha! Yay I got it thanks all, espcially to you deadguy ^_^

Glad I could help. =^)