It's been a while since I originally setup Google Analytics, but I don't remember any security codes like you had with webmaster tools.
So what happens if your competitor reads your Google tracking code and uses it to setup his own Google Analytics with it.
Hopefully Google blocks two sites from using the same analytics code, but the obvious has slip thru security cracks before.
Has anybody tried spying on the competition using this method? I don't want to try it myself, for obvious reasons.