jwolthuis - 9:50 pm on Apr 17, 2013 (gmt 0)
... can I use it for my product ecommerce site that isn't in Google Shopping?
Yes, you can design your taxonomy any way you'd like, but why randomly choose Google's? Why not Amazon's, or your competitors?
You know who your competitors are, so choose your market leader, name your products just like they do, clone their taxonomy, and set your pricing to be a penny less (rounded down to the nearest 0.09).