Donald Reinertsen has written a very good book looking at the application of Lean techniques and Flow to the world of New Product development. He also applies his experience of network design problems to consider how inherently variable NPD can benefit from the experience of unpredictable web and phone traffic. There are lots of principles and a useful cost model. Major lessons are to manage queues and understand the cost of delays and not worry too much about utilisation while reducing the batch sizes of work.
When I have some time I'll list out the key interventions his principles propose for our industry. I can recommend his book.
