I recently added a shopping cart on an information only website.
As soon as the cart went live I started adding links to products and manufacturers from articles on the information pages.
Up to now (touch wood) it has been very successful. Some keywords are #1 with site links after just a few days
One thing I have noticed... Info and money pages were competing for certain keywords/phrases. The internal linking has sent a clear signal to Google and in every case my prefered page is now top dog :)