This is an interesting read, here's an interview
with some of WindowsXP SP2's developers.
But in mid-2003, Microsoft needed Todd again, this time for what would ultimately
prove to be the most secure client product that the company would ship to date:
Windows XP Service Pack 2 (SP2). Recognizing how strategically important it
was that Microsoft get this release right, he threw caution to the wind and
signed on for what he initially envisioned as a three-month project. Over a
year later, Todd and a virtual team of Microsofties that worked outside of the
usually strict hierarchical system at Microsoft delivered Windows XP SP2 to
an eager audience. The SP2 product they shipped bore little resemblance to Microsoft's
original plans for the release, but was instead a far more secure and stable
product that, ultimately, made XP a better operating system.