One of the tenants of TFS is its ability to track work - development or non-development - throughout the life of a project. It comes with a connector for both Microsoft Excel and Project to import and export data to TFS. This is a really handy feature for planning but it kind of falls short when it comes to planning using Agile methods (even though TFS ships with an Agile process template).
In VSTS 2010, one feature I'm really look forward to working with is the new Agile process template, VSTS Process for Agile Software Development. From the bits that have been released so far, it has really embraced the Agile process by aligning the terminology a bit more with the Agile Alliance. Another really useful feature is its ability to do to Release and Iteration Planning through a custom Excel Workbook. If you watch Stephanie Saad's PDC2008 session on MS VSTFS: How We Use It at Microsoft, you'll get to see how this feature works and why it was developed.
Ajoy Krishnamoorthy, a lead Product Planner with the Microsoft Patterns and Practices team, has recently published an article for MSDN magazine that talks about the need for planning, especially in an Agile environment and gives a walkthrough of the Excel Workbook that's coming out in VSTS 2010. I highly recommend that you check out the article and if you haven't already done so, download the September VSTS 2010 CTP and try out the workbook for yourself.