The event celebrating the opening of the "Imagine No Big Boxes" billboard was a great success. If you're driving toward the square on Arsenal Street, look for it at the site where the proposed Walmart would be built, a little bit east of Irving Street. Find out more at http://www.nobigbox.info.
You can read more about the event on the following sites:
The Boston Golobe - Dozens protest plans for a new Walmart in Watertown
WBUR - Watertown Residents Protest Proposed Wal-Mart
WBZ - Dozens Protest Walmart’s Desire To Open Store In Watertown
The Boston Phoenix - Watertown vs. Walmart
The Watertown Tab - Anti-Walmart activists protest Watertown development