Is the voltage supplied by an LCD backlight inverter in a laptop dangerous in any way?
Macbook parts are relatively well known. The backlight driver IC in a Macbook is an TI LP8550. This has a maximum output voltage of 40V.
Not that dangerous.

Traditional CCFL backlight however, create a voltage of several thousand volts. And from experience I can tell that this hurts quite seriously when you touch this.
Dangerous.

In order to get shocked there needs to be a path. A wet keyboard battery powered laptop do not form a path. There is a path when you're holding the monitor chassis with left, and touch the inverter with your right palm.