Some people say it is next to Frank Taaffe's house at 1460 Retreat View Circle. Others put it further north, close to 1350 Retreat View Circle.Here's a video
of a Fox News interview with Sierra McClendon (Austin's sister) in which she puts it at Frank Taaffe's house, 1460 Retreat View Circle. Good screenshots in the video.
During the video re-enactment, George shows where he first saw Trayvon, and it is at Frank Taaffe's house.
More views: here
GZ's neighbor at 1510 Retreat View Circle also says the shortcut is between their houses.
But many put it up by 1350 Retreat View Circle.
Which one would Trayvon have been more likely to enter through?
(Edited to remove link to slideshow. Photobucket converted it to a link to all the Zimmerman photos I posted rather than just those for the shortcut.)