Actually no. The keyboard is still an old fashioned PS2 device on the majority of laptops. It connects to the LPC bus (low pin count - similar to ISA) via a PS2/ISA bridge in the embedded controller. It's just like in an oooooold AT PC. There is no possibility for it to deliver anything but keystrokes. It doesn't go anywhere near the USB stack and can't inject devices or play with the HID drivers.
Keystrokes can be dangerous on their own but engineering a solution to this that assumes the correct state of the machine and can operate software is unlikely simply due to the margin of error.
Connection-wise it looks like this:
http://i.imgur.com/ayFybSd.png
Keystrokes can be dangerous on their own but engineering a solution to this that assumes the correct state of the machine and can operate software is unlikely simply due to the margin of error.