This is a semi-esoteric problem with the menubar AirPort monitor; I've managed to kludge around it before, but it's back. I spent most of last night wrestling with my computer to fix it again -- and in the process, managed to badly hang our router (I was just trying to assign my laptop a static IP! Honest!) and had to reset it to factory default and rebuild our house wireless network. I ended up falling asleep on the floor in front of the router box. It wasn't fun.
Long story short, I'm currently borrowing Kady's laptop -- I'm going to set mine up on an Ethernet cord, but until then, am having a heck of a time getting online. Which is why I haven't responded to any answers to last post's dart riddle yet. Doing so now. (Incidentally, I'm impressed by the breadth of the answers. Two formal mathematical proofs, one complete computer program, and a healthy mix of clever number-wrangling and cleverly applied brute force.)
Those of you who enjoyed working out the answer should also get a kick out of a secondary question that lhexa asked in response. Go to it.