Active directory has been out almost a year now, and is mandatory for the full function of Windows 2000 Server, but it is not yet widely deployed. This could be because it is incomplete, complex and difficult to manage, and it doesn't work quite right. Of course it doesn't support Unix or other environments either, but Microsoft ever intend it to. The complexity of Active Directory has even large organizations who badly need directory services hesitant to implement it. All the technology rags have published articles describing the months of planning needed to succeed.
Consulting firms circle like sharks.
Of course not. To deploy NDS now would be to admit you held up progress in your company for years for nothing. No PHB or corporate drone is going to do that. They're stalling, but eventually they're going to put in Active Directory. It's also a key part of .NET - the future of Windows.