~/.osx updated — sensible hacker defaults for OS X Mountain Lion

That's a long list. I kind of want to run the whole thing just to see what happens...

As with any dotfile repo, I wouldn't recommend installing the entire thing at once. Instead, try and take the time to read through it and select settings that you want piecemeal. You'll end up knowing what everything does, especially in the case that something strange happens and you want to tweak things.

Edit: I should note that I learned this the hard way starting out, I went backwards by ripping out things that didn't work for me/did not like, but not until after making some horrible mistakes!

This is the most important one, that's not been mentioned in OP:

    defaults write -g NSScrollAnimationEnabled -bool NO

It disables the stupid "smooth scrolling". on Lion (and everything before that) you could disable it from the 'General' tab of SysPrefs, but now it's gone.

What does it do? When you press spacebar in a web browser, or fn-downarrow in a text editor, it "smoothly" bring new content up from the bottom of the screen and pushes current screen up.

I don't know, maybe it works great on recent machines, but my poor old 2009 MBP's graphics card is not really powerful, and this animation is not smooth at all. It distracts me a lot.

I strongly suggest you at least try it. If you don't like it, just replace NO with YES and everything's back to normal.

Is there a way to change or disable the animation time when switching between spaces (or "desktops" as they are now called)?

Is it really beneficial to disable disk image verification? What does OS X actually verify when it opens a disk image? It does take some time to verify disk images and I want to be sure of what I'm actually disabling.