One of the reasons I believe that Team System will succeed is that the tool is where it should be. For me as a developer or architect I have all I need inside Visual Studio, for project managers they got at least some important things in Microsoft Excel and Microsoft Project.

Today I also found TeamLook which extends Microsoft Outlook with all the things that is available in Team Foundation Server. For example it looks very simple to add reports to email. Extensions like this will make Team System even more successful, cause many uses Outlook as their primary e-mail, calendar and contact tool.

Note: I have not tested it at all, but the screenshots looks nice.