UPDATE March 2016: The original website with photo and video tutorials and pdf are no longer available.
Written instructions are now contained within this blog post:
The granny shrug is made from two granny hexagons joined together. It can be made in a wide range of sizes from child to adult, just keep adding rounds until it gets to the size you want. Similarly, experiment with yarn type and hook size - you might want to use two strands of 8 ply held together rather than using 14 ply, or might mix a chunky yarn with a finer one.
Have fun crocheting your granny shrug - if you can crochet a granny square you can make this! Wear it with pride!