This Twitter conversation just unearthed another feature that is missing in the Mac OSX version of PowerPoint:
@ideatransplant Unfortunately no trim video options on PowerPoint:mac - Trim Video Clips bit.ly/MeJKHH — Geetesh Bajaj (@Geetesh) July 10, 2012
There are many more, see older posts about PowerPoint 2011 for Mac versus PowerPoint 2010 for Windows here.
I do not think the reason for this is a technical one, it should be possible to write the same software for both platforms. Hence, Microsoft must be thinking that by making PowerPoint 2010 for Windows just that tiny bit more feature rich, it will convince users to stay on the Mac platform.
I think this will be backfiring: Mac users will simply switch to Keynote. Microsoft should create an organizational separation between the Windows and Office business, the latter should consider the Mac a highly profitable platform for selling software.