A few weeks back, Google started testing enhanced Google Maps results. Now, Silicon Valley Watcher noticed it and said that Google was doing something new, by not separating out paid results from free results. Truth be told, and as Danny explains very well at Search Engine Land, Google has been mixing those results, but labeling them.
Here is the search result in question:
The thing is, this is not guaranteeing the top position. Just change the query slightly and you will get that same result, pushed down, because Google's ranking algorithm still determines the spot.
Forum discussion at WebmasterWorld.