I have been onsite in Athens for the last month to do a migration from StarTeam to TFS. We did an install of TFS 2013.3 with SharePoint 2013 on Windows Server 2012 R2 Update 1. This was my first install of TFS 2013.3 from scratch so I thought that it would be a good idea to walk through the process.
You can integrate SharePoint 2013 with Team Foundation Server 2013 at any time and even link to your corporate SharePoint*.
I have been working with a company in Silicon Valley that is doing one of the most complex Team Foundation Server migrations that I think I have ever seen. Just to pile on the complexity they also threw a SharePoint consolidation at me so I caught that as well.
Users coming from a SharePoint 2010 system that try to access SharePoint 2013 after a migration receive a “this site has not been shared with you” message. This mean that they are not able to authenticate to SharePoint 2013.