AW saved my bacon: Key stuck in ignition, but a search turned up the fix...
What happened: I put the Tiptronics tranny into Park, but felt a resistance on the shifter as I did so. Tried it again, same. Stopped the engine, and the key would not come out.
Problem: The most common cause is the silver button gets stuck part way in.
Fixes: I was able to just depress the button with my thumb, then slide my thumb off the edge of the button so that it jumped out. Other fixes included shifting into the Tip gate slowly, then back slowly; or banging on top of the shifter while in Park. One thread suggests that the park sensor may sometimes become damaged.