If you want to subscribe/buy PlayOn, you can get Pandora on your 7MC including extenders. However, I must warn you, it's basically a video stream of the internet application. You cannot interact (thumbs up, thumbs down, etc.) That being said, you CAN have Pandora on your 7MC and 7MC extender.
http://www.playon.tv -- DLNA server that transcodes video streams from Netflix, Hulu, Pandora, MLB, ESPN3 and more
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