I think for an enterprise, the D part of DVCS isn't much of a selling point. What is a good selling point is all of the other stuff that makes Git/HG awesome, like easy branching and merging. There's also Github Enterprise, which if you can pay for it is really fantastic.
The D can be a selling point. Some things D enables:
Working offline is completely transparent. If your employees are on an airplane, or if the wifi at the conference they are at is overloaded, or if the central repository goes down for some reason, people can continue to work normally.
Code review based on asking for permission, not forgiveness. While the UI is a bit horrid, gerrit has been a huge win for us when it comes to code reviewing changes before they are out "in the public". When code review happens after something gets committed to the main repo, it's far to easy for issues to get forgotten about and never addressed. (Of course, Github pull requests have a better UI than Gerrit, but you might have reasons not to want to entrust your code to Github. And, also of course, this isn't strictly something that can only be done in a distributed VCS, but it seems to be a lot more natural in that context.)
