ESPN radio app does have several live stationsn (under the "stations" tab), the podcenter (not live), and also live sportscenter.
It's awesome. I have Sirius radio in my office and have had both on at the same time. There is a little lag, about 15 seconds.
I love it!
<edit> by the way, it will run in the background while you do other stuff. It even pauses while you take a call.
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