Some good questions! I don't know if major U.S. firms use rerefined oils in their products, although a very few oils like Union 76 Firebird brand oil are trumpeted as such. Through a quick search I found other interesting info as well:
Other than rerefining, used oil is used for:
43% asphalt plants
14% industrial boilers (factories)
12% utility boilers (electric power plants for schools, homes, etc.)
5% cement/lime kilns
5 % marine boilers (tankers or bunker fuel)
4% pulp and paper mills
"The re-refining process removes additives, dirt and contaminants, leaving a pure base lubricating stock. New additives are then blended with this pure base stock to create a motor oil that meets car manufacturer warranties and American Petroleum Institute (API) specifications...Used oil can be re-refined because the base lubricating stock doesn't wear out or break down with use-it just gets dirty. API-certified re-refined oil is endorsed by Ford, Chrysler, General Motors, Volvo and Mercedes-Benz, and Mercedes-Benz uses it in all its German-made cars as factory fill. Also, the 1996 NASCAR Winston West Champion race car uses it."
"Manufacturers also may label the oil 'recycled' to attract environmentally-conscious consumers, but they DO NOT HAVE TO add any qualifiers such as 'used' or 'rerefined.'" (It appears that rerefined oil doesn't have to labeled as same.) http://www.ftc.gov/opa/1995/10/uoil2.htm
"Our audit revealed that while re-refined oil can meet API specifications, not all currently labeled brands do actually meet the standards. API is not a reliable guarantor of quality with regard to bulk oil, and there are overall weaknesses with the audit program." http://vendornet.state.wi.us/vendornet/recycle/4perf24.asp
"Once the engine, which had 318,000 miles logged on it, was revealed during the teardown, it was in virtually new condition. Daniels credits quality lubricants such as 76 Lubricants Firebird 15W-40, a product of ConocoPhillips Company, as “one of the driving forces” behind the incomparable engine wear. Daniels noted little wear, including limited bearing wear, no visible sign of cylinder wear and no sludge build up on the inside. Once again, the re-refined oil had proven itself to the technicians at Kings County Metro Transit that it could perform as well as, or better than, their previous stock."