If you want to know what's going on with supply chains you could do worse than to take a look at 2 of the heavyweights with whom we're all familiar: Amazon and WalMart.
Dan Gilmore from Supply Chain Digest has a multi-part series going where he's interpreting their numbers and divining what they're doing with ecommerce, global operations, and a number of other areas of interest. One conclusion is that fulfillment costs are high for Amazon. Check out the first two articles
HERE and
HERE.