Hmm I had to look this up to see what it was. I'm not immediately taken with the effect, but I am open to trying things out and shall give this a go (digital) as soon as I get the right photo which I suspect will be soon.
The technique is to take pictures over a period of time, then in Photoshop or Paint Shop Pro to combine the red, green and blue channels of separate exposures into one final exposure. Works with clouds, water, etc.