We plan to provide migration tools for users switching to TFS.  A VSS user asked in the newsgroup about migrating VSS labels, revision history, sharing, and pinning.

The goal is migration of all data, consisting of projects, files, and folders, with associated metadata reliably with minimal information loss while preserving user information and appropriate permissions.  There are some features in VSS that do not translate to TFS.  The following is quick overview of the preliminary plan.

• Users and groups in TFS are Windows accounts (it uses standard NTLM authentication).  SourceSafe identities will be migrated to Windows accounts. 
• Labels and revision history will be preserved.  With regard to revision history, TFS supports add, delete, rename/move, etc.  It does not support destroy/purge in V1.
• TFS does not have the equivalent of sharing, so the current plan
  is that the migration tool will handle that by copying.  Each copy will have its own history of the common changes made after the file was shared.  VSS branching is migrated in a similar fashion.
• Pinning and unpinning are also not available in TFS.  The current plan is that for any item currently pinned, the user will be given the option to either ignore the pinning or to assign a label to the versions that are pinned and lock them.
• TFS does not support the VSS archive and restore features.

That is a very quick summary of the plan, which may change.  We welcome your feedback.