The Windows 8 Developer Preview also uses GB, it's likely the final version will as well.
Another forum post about GB and GiB:
http://social.msdn.microsoft.com/Forums/en-US/windowsdeveloperpreviewgeneral/thread/83643ab9-f1ed-4524-a42a-c3a06f198820
Windows uses "GB" instead of "GiB":
http://connect.microsoft.com/WindowsServerFeedback/feedback/details/356695/windows-uses-gb-instead-of-gib
Feedback Tool See this link, it takes you to the Connect website where you can download and use the feedback tool to submit feedback: https://connect.microsoft.com/site1147/InvitationUse.aspx?ProgramID=7221&InvitationID=ADD1-RY34-K4T4 If you are prompted for an invitation code, please enter the following key: ADD1-RY34-K4T4 From: http://social.msdn.microsoft.com/Forums/en-US/windowsdeveloperpreviewgeneral/thread/38727d4d-99d2-4b88-bb22-5271c28a8f14#6a1ceb32-d519-4844-9d80-053caf6b7226