I know there was one at the Hilton that took MasterCard/cirrus as of aug 2012. Also in the building on new-bole/telebole rd with the movie theater on the ground floor and at the Sheraton a year or so before that.

Be prepared though for power outages and machines out of cash. Have a backup plan. I was stuck getting a cash advance due to a problem with phone service limiting a hotels availability to accept credit card and first ATM I went to had no cash in it.