WSJ has an article about how the Quality Gates came about. One of my personal beliefs (in addition to some that were stated in the WSJ peice) was that test in windows had a much heavier workload dealing with xpsp2 then most dev teams, which meant that developers focused on Longhorn while Test was focused on xpsp2. Code was getting checked in and the normal quality controls weren’t getting followed. Each new build of the old Longhorn, just kept getting worse and worse until eventually the decision to restart had to be taken. At the layer of the OS I work at, we more or less didn’t lose any work outside of proving that our code met the new quality gates and checking it back into the product.