What are "GPS Shortcuts"?

The other day I was driving around in Saints Row the Third and a message appeared just above the mini map saying "GPS Shortcut unlocked!"

What does this mean, what does it do and are there any other unlockable "shortcuts"?

The GPS in Saints Row: The Third will generally give you shortest path directions to wherever your current objective or map marker is. This GPS is represented by the green line on your radar, and you'll also see green arrows on the main display showing you turns you should take to get where you're going. At the start of the game, however, it will only know about the major roads and thoroughfares of Steelport.

As you careen around the city, smashing through parking lots, alleyways, and other less-traveled paths, you will see this "GPS Shortcut unlocked!" message. What it means is, that later, when the GPS is routing you through an area, it will know about this shortcut and use it in order to provide you with a shorter (but potentially not faster or safer, depending on the shortcut...) route.

Finding a number of these shortcuts is also one of the Saintsbook Challenges in your cell. These challenges are also tied to the achievement "You're my Hero!" You don't need to find all of them for this challenge, I believe it only requires something like a quarter of the available shortcuts to finish.

You can see how many shortcuts there are and how many you've found on the phone. Go to the "Extras" button, and then select "Stats" and move to page 5. On my Xbox 360 version, there are 263 shortcuts to find.

Now that you already know what are GPS shortcuts, you might want a map of them.

LancetJades built such map and posted in GameFAQs boards. The map is available here: http://www.evermoreforums.com/johnny/info/sr3_gpsmap.jpg