Pedro has build one of the best apps for Windows Phone 7 (WP7) that I have ever come across - TFS on the Road . As the application navigation map shows below it covers most aspects of TFS that you would be interested in – all packaged up in a very nice GUI. :)
Before you go away and install the app, you need to have TFS OData Services installed and made available over IIS. If you are using CodePlex, then you are good to go as Microsoft already has that switched on.