VSCommands 2010 Lite is a free extension for Visual Studio 2010 which now includes StackOverflow Notifications in a form of a toolbar button which periodically checks SO for new badges, messages and reputation changes.
Once extension is installed in Visual Studio 2010 go to Tools->Options->VSCommands 2010->Other Settings where you can enter your user id and specify the period for which notfications should be checked (Today, Last Two Days, This Week, This Month).
VSCommands Lite is free to use.
Visual Studio 2010 extension
Visual Studio 2010 SDK + Stacky