Today I was asked about transferring data between the workflow and the host application. Because workflow instances run in a different CPU thread to the host application data transfer is an important consideration. In WF Beta 1 you added parameters to the workflow in the workflow designer.
In WF Beta 2 we still have parameters, but they are defined directly in the workflow class file in code now. Any property on the workflow class can be a parameter. You can also use events implemented in the HandleExternalEvent and CallExternalMethod activities or you can use a custom event activity.
Both of these methods of data transfer are shown in Lab 1 of the Workflow hands on labs for WF Beta 2 which you can get here.