I always sent my engine blocks off to have them Nikasil'd. Really made a difference in the resistance. With the block on a stand, with crank, rods and pistons installed, I could spin it by hand and watch it slow to a stop.
But, then again, that was on big outboard engines (2.4-3.4L V6 turning 9-10,000 rpm).
Friction reducing and thermal barrier coatings aren't new. If you're considering using coatings in your next engine build be sure to think about all the parts and how they must work together as a system. For example, if you coat just the piston tops it will reflect even more heat back to the valves which could be detrimental. You want to ensure that everything is well and evenly insulated to avoid hot spots. Coatings also add thickness which must be accounted for.
I've been E-mailing Swain back and forth about that, as I'm planning on sending them my pistons. I cant afford to have everything coated, and they advised that coting the pistons would be my best bet. One of the Protege guys on m.net did the same and it turned out well.