Adhesive for concrete board and tile

[Fishboy]

I was watching one of those DIY channels the other day and they were laying floor tile. They used an adhesive like Liquid Nails to put the concrete board down on the floor before they screwed it down. This got me wondering why I use thinset to lay concrete board, and why I don't try something like one of these new adhesives. After all, aren't you just trying to get the tile or concrete board to adhere to the underlying surface?

I'm much interested in your opinion, particularly in using something like this for an outdoor application.

Aloha pumehana,
Brian and Mary
Lynnwood, WA\Discovery Harbour