My first impression was that the Sharingan eye wasn't crying, but just leaking fluid or something after the recent operation. Just reacting to the recent change or something. But I guess it could be symbolism for Obito joining with Kakashi.
leaking fluid? hehe thinking too hard there. Its real tears.

The Tears symbolize Kakashi's break with his old insistence that a shinobi is a souless weapon.

"Those that break the codes of the ninja world are known as as trash, but you know what? Those who don't take care of those comrades, they are lower than trash."

When i saw kakashi cry, that was the first thing that went in my head.


That is my favourite quote in naruto btw. [img]i/expressions/face-icon-small-happy.gif[/img]