While the folks in Redmond would prefer an all-Microsoft world, their investment in Vintela shows that they know it isn't likely to happen.
Microsoft and Vintela are working together on technologies that allow Microsoft's Active Directory to manage users on other platforms, as well as ways to allow Active Directory to manage nix objects. Vintela also sells products on its own that allow Linux/UNIX users to authenticate against Active Directory, and for Microsoft's Systems Management Server (SMS) to work with Linux, Solaris, Mac OS X and other nixes.
I'd like to see more of this kind of thing from Microsoft. I know a number of people who think Microsoft's Active Directory is the greatest thing since sliced bread, but living in an all-Microsoft world simply isn't an option. A little less lock-in, and a little more cooperation is the kind of "innovation" I'd like to see from Microsoft.
Now, where's that Linux port of MS Office?