[r4pha]

You can see the "git diff" between two nodes if you click with the right button on a node and with the left button in another one. For example:

http://srctree.net/3S-2

Maybe I need to think of a better way to present this!

[Ironchefpython]

You should have a compare with button, and when you click the button the mouse cursor changes, and then clicking a tree node will set it as the "compare to" node.