Technet shares key information related to this recent change
Microsoft – Corporate Logo revised http://blogs.technet.com/b/microsoft_blog/archive/2012/08/23/microsoft-unveils-a-new-look.aspx
QUOTE: It’s been 25 years since we’ve updated the Microsoft logo and now is the perfect time for a change. This is an incredibly exciting year for Microsoft as we prepare to release new versions of nearly all of our products. From Windows 8 to Windows Phone 8 to Xbox services to the next version of Office, you will see a common look and feel across these products providing a familiar and seamless experience on PCs, phones, tablets and TVs. This wave of new releases is not only a reimagining of our most popular products, but also represents a new era for Microsoft, so our logo should evolve to visually accentuate this new beginning.