What would be cool is an OLED keyboard where what each key would be changes depending on what program & language you use. Like if you speak English and someone else who uses the computer speaks Arabic, they don't have to switch out keyboards. Plus, for some programs like Photoshop, one key might be for the paint brush and another for text. Or, even better, a multitouch screen so each button could be individually sized depending on user prefs. Something like Star Trek.
I don't particularly like the MacBook keyboard. If it stays a standard keyboard, I'd want a full size keyboard w/ the full number keypad and Page Up/Down, Home, etc. keypad. Also, power button, upgrade to USB 2.0 ports. One person said here add flash drive support. I've been able to use flash drives w/ current (and even original G3 iMac) keyboards. Slow as heck, but it worked. Backlighting would be nice, too.
Changing the keyboard layout per application sounds like a great idea. At least one can do the following. In each app, there're usually quite a couple hot keys that are handy. But it's always a big pain trying to remember them all. On a virtual keyboard, each app can display some sort of hints, text or graphic, on the corresponding keys and that must be awesome