I was in a Watertown MA supermarket at about 5 when my mother, who lives an hour away, called to tell me she saw this on TV and Watertown was affected.
I went to the bottled water aisle to get water for my family. It was mostly large packs of bottles. I managed to get 15 gallons in big jugs by going in the direction I saw a guy with jugs come from. They wheeled a cart with water out, and people were pulling it in boxes straight from the cart. At first, maybe 3-4 people were loading up on water, but that was it.
Within the 20 minutes I was there, I watched the shelves almost empty completely of water.
One nice thing--the supermarket manager, before I even got to the checkout, had discounted all the water--thank you Shaws!
The psychology of it was interesting. I felt bad about the jugs (I am I hording? should I share) but then thought how I would feel if I didn't have enough clean water for my pregnant wife and child, and family who is visiting for the birth. I calculated that I would feel like a bigger jerk if I didn't look out for them, so I went with it. I also called several friends and gave them a heads up on the run on water. One of them didn't know, and was able to find some at a CVS. So that is my story so far.
The article I just read said that the pipe was a "custom pipe" that burst, so they have no replacement ready and can't even give a timeframe.
edit: on the news they now think it was just a "connector" so it may be an easier fix.