I just got a Samsung Galaxy Tab 10.1 and want to test my app on it. I turned on USB debugging and the bumblebee in the corner confirms that it is on. When I run my app from Eclipse (Helios) on Windows 7, I don't see the Galaxy Tab in my list. All I see is my Samsung Nexus S, which is also attached via USB.
You may need to install suitable drivers on your pc.