The Samsung Multi Media dock has a headphone jack on the back of the unit and uses the microUSB as signal. Basically a partial teaser for the possibility of still adding TV-Out to the Epic, but that's for another thread.
Personally I want a Samsung dock, but I'm not willing to pay $35 shipped for it from eBay when to me it's worth easily half that.
It does have a headphone jack in the back, but it doesn't work... at least until 2.2 comes out.