Besides the stand/cart you mentioned between Canada and the UK, there is an identical one in Future World. You go to your left through Innoventions passageway toward Mission Space and it is immediately on your left after you get through the passage. We found these carts to have the best espresso drinks on property. Fountainview Cafe at Epcot is also good.
We were really pleased to find one of those espresso carts at AK park. Right when you get off the tram from the parking lot it is to your right before the ticket windows.
Also, Typhoon Lagoon had one. It was past the locker rental area, just over the bridge toward the wave pool and a little to the right.
At MGM there was a cart when you exit the Tower of Terror gift shop. Also, there is Starring Rolls Bakery.
At MK park - nothing but the Nescafe !@%$*&!