Having visited the site on a computer I use for security work and is about to be wiped, it links to a git hub repositry. The readme says the following:

Mainland users do not need to over the wall,
Directly log in to the "gate" website,
You can share the world's best resources.
"Network" opened a new era of network perspective,
Leading the new era of network fashion.
"Door" for mobile phones, tablet, computer and so on
All network end users.
"Gate" no need to break through the wall to block the network,
Is a stable and long-term security website.
Just keep the URL in your phone's browser bookmark,
Or saved in the computer browser favorites,
You can always open the "door"
Share the world's resources.

It appears to be a github program designed to allow mainland chinese users to break free of the censorship of their internet. Basically a proxy intended to give people access to uncensored internet....

Probably really really illegal in china, but interesting.

Git.io is ok, its a repository for code. The actual program this particular github has developed though, I would have to look more into to tell you. I wouldn't download the program, because if it DOES do what it says, somone is a pretty skilled programmer to break out of the chinese internet censorship, and could hide other things in it. If it DOESNT.... well then there wouldn't be much point circulating the address unless it was a scam.