Free OSX Upgrade?

I'm currently borrowing a mac off a friend to program some ipod apps. Xcode requires at least OSX 10.6.6 which I found on mac's website for $18.99 or something around there. But on osxdaily I found a free direct download. My question is is there a legit free download to upgrade mac osx or are the options illegal?
 
It is probably just a link to a copy of the iso.

It still needs to be purchased against the apple ID of the owner of the laptop or it is illegal to download and use, whether it works or not.
 
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