What exactly is IR, and what does it do for your photos?
IR means infrared. I don't know how familiar you are with this, but there's the visible spectrum and invisible spectrum, infrared light belongs to the invisible. You eyes and your lens can only see some of the light. For the camera to see infrared light you need a filter or IR film. It's kinda hard to explain, but this is what an IR image looks like.
One more example
here.
The end result is often quite different, as you are really recording the heat of things more so than the visible tone - so living things tend to appear whiter (hence the really white trees) and so on. Portraits can look very cool/ odd using IR as it gives the skin a very clean, alabaster look. You need either fast IR film or a camera without the hot filter (like I assume June wants to remove from the D30/D60) to get 'normal' speed exposures for IR, which you need for example to shoot IR people pictures. Otherwise you are left with very long exposures on most digital cameras, as you normally want to remove IR from the captured light.
