The MSBuild team is not the only one doing Agile development. Several other teams are using Scrum. At least according to Rob Caron:

"Something interesting happened this last week. Ken Schwaber visited Microsoft and several Microsoft groups presented their experiences with Scrum. This event sparked a large interest in Scrum from more teams. Our own team has already been pinged several times this week from folks in different groups asking about where to get more information on Scrum, how we do our reports, and even if they can sit in on a daily Scrum."