Skype listens on port 80!

Well, I had a little fright today. I tried to start up my Apache dev server on my PC and it said port 80 was taken! Now my internet connection hasn't been behaving itself recently, so I've been running TCPView (part of sysinternals) all the time anyway. A quick look at the list of connections there told me Skype was the culprit. Sure enough, if you look under Tools -> Options -> Advanced -> Connection in Skype you'll see a tick box called "Use port 80 and 443 as alternatives for incoming connections". Obviously it's a way of getting through firewalls, but I'm not sure it should be on by default without me ever being told!