Recently, I've been tinkering with electronics hardware. Let me tell you, for someone who's more comfortable with software, the experience can be quite scary: if you mess up your code, the worst that happens is that it fails to compile, or maybe the interpreter spits out an error. But this electronics stuff is real! If you do something wrong it could literally blow up in your face.
Fortunately, for people like me, there's the Arduino project to hold your (badly scorched) hand. Doubly-fortunately, you can still use your favourite powerful text editor to do so. To get syntax-highlighting working in vim for Arduino's .pde, you have to install a script written by Johannes Hoff. The Arduino project is constantly changing, so I updated the syntax file to add some new features (notably some stuff relating to the Arduino Mega).
The updated version is now available on vim.org. Hopefully it will prevent some explosions (or, more likely, bricked microcontrollers).