A great article on six sigma here. It studies the history of Six Sigma (Deming and Japan), its association with Motorola and GE, a hilarious send-up by the TV show 30 Rock, and the variability of certification.
I remember working with the Six Sigma people at Microsoft. I didn’t understand how it was supposed to work there. Microsoft, like most American tech companies, manufactures nothing. All manufacturing is outsourced. And they produce very manufactured goods outside of the Xbox. It was odd to see Six Sigma applied to order processing and customer service.