I actually started thinking about making a coconut stout myself a few weeks ago (before seeing it here). I have actually tackled it slightly differently.
1.7kg Stout Extract, 1kg Dark Malt (Dry), 250g Cracked Choc Grain, 2 x 50ml Coconut essence (cake decorating section of supermarket). My thought is hopefully it will come out something like a "Bounty"

. Smells awesome while I was mixing it all together, and the inital fermentation bubbles make the house smell like a Thai massage parlor. mmmmmm.......coconuty.......
I have done a similar recipe once before using a handful of fresh split cherries (boiled for about 15 mins and then put in a stocking inside fermenter). Came out beautiful. Like a "Cherry Ripe" kinda

.
I am excited to hear how the real coconut goes. My worry was the oil content of the coconut, so that is why I went with essence instead.
Will watch this topic closely, and will post my efforts online when it finishes.