Well, my samsung s3 is not detected as android device but as portable media player gt-19300
http://cubixshade.com/images/s3.png
I set "Always prompt to pick up device" on Eclipse Run Configuration and when I run the application, no device is shown or detected.
How will my phone will be detected as active android device in eclipse ?
I solved this issue for my Samsung Galaxy y S5360
by installing Samsung Kies from here. And you would be able to sync your Samsung mobile with your PC and it includes almost every device driver for almost every Samsung device in the market. And then your device should be recognized by Eclipse. It is a worth a try.