I think the advantages of a distributed version control system are apparent on any scale. I'm going to refer to git from now on, since that is the DVCS that I have the most experience with, and it's easier to say and read than DVCS.
I really look at the advantages of centralized version control systems as a subset of the advantages of git. If you want to have a central repository with git, go ahead. It can be on a server if you like, just like your SVN server; or it can be on a network drive, or even a usb stick. You can connect to your central repository commit, just like you can with CVS; or you can spend the day working in the park without an internet connection, commit all you like, then push to your server at the end of the day. I prefer the latter.
My development team is small, we vary between 3-5 developers depending on the project we are working on. Our work environment has strange constraints that make a centralized system difficult to implement. Instead we use Git to allow us to coordinate our work between the various independent networks we develop in. The real advantage of Git, or any DVCS, is that it lets you stop thinking in terms of physical development resources: servers, developers, parks; and frees you to think purely in terms of branches and time, which are the true dimensions in VCS space.
That's all I have to say that's somewhat original, here are some links that should prove more informative: