Pressing "P" while driving??

[gipper]

My wife and I were on our first relatively long road trip (2 hours) in the x5 yesterday and I noticed that when I reached for my drink my hand would graze over the gear shift joystick. I noticed that I was actually grazing over the PARK button. So I asked her what she thought would happen if I hit the button at highway speed, or any speed for that matter. She looked in the manuel but couldn't find anything. We decided we didn't want to find out the hard way. Now the whole ride home I had this urge to just hit the button to see what would happen.

I figure its electronic so there must be a speed sensor that wouldn't let it engage or something. Does anyone have any insight so I don't have to go crazy and finally just end up locking up the tranny at 60mph???