How are the samples from the 2.0 API integrated into the SFV 2.0 in Flash Builder 4?
The API samples, like any other Flex applications, can often be re-purposed as a widget in the Flex Viewer framework. If you're familiar with Flex development, take a look at the basic instructions at
http://help.arcgis.com/en/webapps/flexviewer/help/index.html#developers/hellowidget.htm for creating your own widget.