What is Baseline4TFS?  It is a module of inteGREAT4TFS

Baseline4TFS is a web-based solution that easily provides baselining of TFS work items. This tool provides users with the ability to view all baselines and compare between the older and the latest versions of work items. Having a baseline on each project allows users to monitor current project performance, manage release scope and also to improve the accuracy of future estimates.