How It Works
How it works is actually pretty simple. CapsLockBeGone makes an entry in your registry that remaps your keys and tells Windows to ignore your CapsLockKey. The key in question is:
From there, the entry is "Scancode Map", and the value is a bunch of binary values that map to key values.
If you are really curious, the values for the entry are:
The '$' in front of the number there indicates that the value is hexa decimal value. The application basically writes those values into a binary value inside the key above. Once Windows sees that (you have to reboot, as the appliation will tell you), then you'll get no CapsLock key.
Strictly speaking, you don't need CapsLockBeGone -- you can enter the values yourself, and there are plenty of *.reg files out there (Google for the "remove CapsLock key" and you should find them), but this application does it pretty painlessly and without worrying about mucking around in REGEDIT.EXE or with *.reg files. And of course, it does -- reluctantly -- allow you to set things all back to normal.
What It's Written In
CapsLockBeGone is written in CodeGear Delphi 2007 for Win32. I'm the Delphi Product Manager for the product at CodeGear, so I darn well better use it, eh? Despite my obvious bias, I can confidently say that Delphi is the perfect tool for this sort of thing. It creates fast, native EXE files. It uses component-based RAD development to build applications, so putting this together was relatively fast. CapsLockBeGone doesn't require any additional runtime libraries other than what comes with Windows, so the distribution for it is nice and small and the EXE should run on almost any version of Windows -- even Windows95.