Associated Food Stores, a Utah-base food distribution company was ranked No. 9 in the InfoWorld 100 for wireless networking.  The write-up says:

Farr West, Utah, is home to AFS' 600-acre distribution center and massive wireless networking deployment that locates, tracks, and manages assets. The network uses WhereNet's Real-Time Locating System, which works with wireless LANs and bar code data-capture tools and rides on AFS' trailers, tractors, and dollies, to provide AFS with up-to-the-second location and telemetry information on the hundreds of vehicles rolling through the center. Led by Tim Van de Merwe, Internal Logistics Manager, the wireless system returned AFS' investment of several hundred thousand dollars in just six months.

I'll have to go visit and see for myself what they're doing.  Sounds like a fun field trip.