A group of us from the Phoenix Atheists Meetup had lunch today near one of the billboards and used the occasion for a photo op. This is one of the five billboards, which, contrary to my earlier descriptions, are all of the "Imagine No Religion" design. Too bad, I would have liked to have seen the "Beware of Dogma" design up, as well as the "Keep Religion Out of Politics" slogan. (If I obtain permission, I'll update this photo with one of the group shots, which can be seen at the Phoenix Atheists Meetup site.)
There's some additional coverage in Ed Montini's column at the Arizona Republic.