Ken recently asked the question:

“Do we have documentation that I can review and send to a customer on provisioning users in a VSTF setup with no AD integration?”

The answer (from our soon-to-be-released-and-therefore-preliminary-documentation):
…Managing Team Foundation Server in a workgroup environment is possible but can present some challenges. Active Directory environments are recommended for most Team Foundation Server deployments. If Team Foundation Server is to be deployed in a workgroup, it should only be deployed in workgroups with a very limited number of users and computers. See the article Managing Team Foundation Server in a Workgroup.

Thanks for the question Ken.
-Lisa