Visual Studio 2010 released with workflow foundation 4.0. Workflow Foundation 4.0 is introduced a significant amount of change from the previous versions of the technology. The change varies from the core of the workflow foundation, runtime and tools. Workflow foundation 4.0 re-architected to improve the performance and productivity of the WF.
One of the major changes in Windows Workflow Foundation 4.0 is the Activity Designer. The new Activity Designer is based on WPF.
For more details, please refer http://www.dotnetfunda.com/articles/article963-activity-designer-in-workflow-foundation-40-.aspx