We went live this weekend in Production on Yukon Beta 2.  Microsoft runs SAP internally to support the core business functions of the company.  We have one instance worldwide of SAP R/3 Enterprise (4.7) and are running the Sales/Distribution, Finance, Material Management, Treasury, Project Systems, Real Estate, Controlling, Payroll, Benefits and Organization Management (HR) modules.  We also use the APO, GTS, BW and SCEM applications.

The upgrade to Yukon went smoothly.  We'll be writing some whitepapers on the upgrade experience and some of the technologies we'll now be able to leverage on our SAP implementation, such as mirroring.  Detailed information on our internal SAP implementation is published at http://www.microsoft-sap.com.  We also run (free) periodic customer and technical workshops.