Google did not immediately respond to a request for comment.
It's a funny, clever little joke but one that's not necessarily difficult to pull off. Google Maps, particularly when it comes to business listings, relies heavily on user-submitted content. So one could have easily made a listing for "Edwards Snow Den" at a different address and then submitted an address change for 1600 Pennsylvania Avenue.
There's actually also another business listed in the White House, a law firm called cCross. There's also a listing for "freddy fazbear pizza" within the U.S. Department of the Treasury building, presumably a reference to the Freddy Fazbear horror video game series.
Google has several ways to verify businesses, including by sending postcards or by calling a business's listed phone. Still, there are plenty of businesses that show up on Google Maps that are a little bit misplaced, or -- in this case -- nonexistent. Users can report closed or moved businesses by clicking the "Report a Problem" link on the map service.
In any case, if Snowden were chilling at the White House, he wouldn't advertise that fact on Google Maps.
Update: Google has removed the fake listings from the White House and the Treasury building.