"Sorry, but I have to whole heartedly disagree. I used cedar planks for grilling salmon quite often a year or two back. Soak them, spray one side with pam or similar, and lay the fish skin side down on them. Grill at around 350 over direct flame. There is definitely a unique flavor imparted, and the boards are prone to burning. It is not intended for smoking low and slow. The whole process takes maybe 20 minutes if it is a thick piece."
Interesting, going to have to try this.
As for if it does or doesnt add flavor, sound like an experiment needs to be done!!
You would think that it does as it has become real popular the last few years, but I have never done it.