Slightly tangential, but the author mentions remapping Caps_Lock, as I do (I've mapped it to Escape, as Esc used to be where Tab is on modern keyboards anyway). The moment I first did this, I realized how amazing vim really is, and why people always say that you can navigate the entire file without moving your hands from the home row.
However, both methods I know for doing this only work inside an X server - does anybody know a good way to remap keys without X?
I used to have it mapped to escape but once I started using tmux I mapped caps lock to control and never looked back. Much more versatile than escape and ctrl+[ will do the same thing (although it's proving hard to break the habit of pressing escape instead).
Best of both worlds: KeyRemap4MacBook has a setting where Control acts as Control when held down, but acts as Escape if typed alone. This in combination with setting Caps Lock as Control in OSX is all sorts of awesome.
Under OSX I used a tool called KeyRemap4MacBook which adds an item to the control panel that lets you reconfigure keys. I just tested it, you can can disable the escape key, but Ctrl-[ still works like you'd expect.