According to the embassy's announcement on Facebook, U.S. citizens who "find themselves in distress" while in Austria due to, say, a lost or stolen passport can simply enter any McDonald's and "staff will assist them in making contact with the U.S. Embassy for consular services."
Those whose G.I. tracts wind up in distress from visiting McDonald's are apparently on their own.
What you will get, reports the New York Times, is a "24/7 hotline number for the United States Embassy and a phone to call there if needed."
A McDonald's spokesperson told the Times that those seeking help will not be required to buy anything.
Judging from the comments on the embassy's post about the new program, many people are lovin' it (badabababa), though the prospect of a corporation becoming involved in government services makes others Grimace.