travelzoo's response sums it up well. Yes, the Focus can be flat towed, but you HAVE to disconnect the battery. Not doing so can result in major transmission damage. IIRC, the cases of transmission failures noted on here in the past, were from folks that didn't disconnect the battery properly.
This was actually one of the main reasons we chose NOT to get the Ford Focus, and went with the Ford Fusion hybrid. I did not want to have to fool with disconnecting and re-connecting the battery, and having to reset things in the car every time after towing. With the Fusion hybrid, you don't have to do any of that. You just hitch it up, put it in neutral and go. Thats the way I like it. :)