Epcot -- there is a coffee stand way in front of Ellen's Universe of Energy -- not near the doors, but where you turn off the main path to head towards it.. When you place your order, your back is to test track.
DTD -- I think there is a stand to get decent iced coffee there too. It is right outside the World of Disney -- the princess room doors, along the water.
Poly -- we stayed there for 11 nights in Dec 2006 -- I wasn't able to get coffee from that stand even once! In the AM it was either not open yet, or completely mobbed. In the evening, it was never open. I was so disappointed.