In Honeycomb some of the System apps have a "preview" of the widget when you click the "add" options on the home screen.
How do I go about adding a thumbnail/preview of my widget to my application so the user can get a feel for what it looks like when adding it in Honeycomb?
If you run the android emulator against the Honeycomb sdk, you should see an app called Widget Preview, which will allow you to pick the widget to take a preview of (you will have to install your widget on the emulated device). I think you can also build it yourself if you have the source checked out (it's under development/apps/WidgetPreview).
http://developer.android.com/guide/topics/appwidgets/index.html#preview