Too simple to simulate?

One of the biggest current uses for high performance computing (HPC) in manufacturing is for simulation.
Simulation allows you to experiment with potential process or design factors without the expense of prototyping. The problem with simulations is even with a fairly powerful single CPU server, they can take days or longer to run. With the move to simulations on parallel CPU computers, simulations can be run and ready for analysis in hours rather than days.
Dr. Roy Orbach, Undersecretary of State for Science, calls simulation the third leg of innovation. During an invited talk at SC07 in November, he cited the examples of Boeing, Pratt Whitney and Proctor &Gamble as manufacturers who have very successfully incorporated simulations into their manufacturing processes to give them a competitive edge. With the use of simulation of manufacturing process, these companies have reduced time to market and lowered the cost of first prototype.
You are thinking to yourself "that is all well and good if you are manufacturing jumbo jets, race cars or semiconductors, but all I make are little plastic widgets. My products are way too simple or inconsequential to require a simulation". Instead, ponder the expenses invested (and potentially lost) in improvements if you do not do simulations first.
Trial and error changes mean production and time costs for trials that fail; cardboard cutout or prototype changes have increased costs for the building and testing of the physical prototype, as well as shop time and expense. In many cases, a simulation can be run on an x86 linux cluster for very little cost other than the investment in support and knowledge of simulation process. These are upfront investment costs amortized over many simulation runs versus the sunk costs that are lost when doing trial and error or prototyped improvements. This low cost clustered hardware solution has been used and documented since the late 1990s, and has become mainstream, with even the Kuwait Oil Company recently moving to a sun/linux clustered solution for simulations.
With that knowledge, the INCITE program has also been offering government facilities for manufacturers wanting to try out simulation on HPC infrastructure, or looking to test viability before investing in their own infrastructure. Simulation is seen as a manufacturer's single biggest competitive edge by the council on competitiveness, it is labeled as an "innovation accelerator."
Suzie Tichenor of the Council on Competiveness calls modeling and simulation "the key to building an innovation culture". Being able to simulate changes before implementing them can make it faster and cheaper to make the right decisions on process or product improvements‑providing true innovations on the plant floor. As plants push for extreme lean JIT manufacturing, every small performance tweak along the manufacturing line can have a big impact on the bottom line.
Are you using simulation at your manufacturing facility? If no, what are your limiting factors or barriers? If yes, how are you using it today and where do you see this growing?