This seems like the right thread and the right timing to re-introduce this photo. The surprising LACK of media hoopla surrounding the HM opening, which Todd describes, probably explains the dearth of publicity materials. He is correct that the newspaper coverage, including reviews that appeared after the ride opened, just recycled publicity photos that Disney had sent out in the Spring.
So you look in vain for opening day photos and such. Well, almost. Take a look:
I am fairly certain this is a grand opening photo from the 12th of August. I get to that conclusion by a circumstantial argument, so it's not airtight. But consider:
1) The copy of this photo that Davelandweb has is stamped "August 1969." The Haunted Mansion: Mansion publicity photo, August 1969
2) It's not staged. Do you see the CM in the center, facing left? He's at the turnstyle, prepared to collect tickets. That's where they did it in the old days. If you were a professional photographer and you were setting this shot up, would you put him in? He adds nothing to the ambiance and only makes people ask, "Hey, what's that guy doing?"
3) It's a special occasion. They've got CM's posted like sentinels out front. They don't "waste" CM's like that under normal conditions, but for special occasions they sometimes do that.
4) The people are not waiting for their turn on an already-open ride; they are waiting for the ride to open. How can you tell? With even the slowest moving line, the overwhelming majority of the people will be facing in the direction of movement. Here, hardly anyone is facing left. The situation is static. The ride hasn't opened yet.
5) There are no children in the line (maybe a teen on the far right). No one knew yet if the HM was "safe" for little kids.
6) This is a very professional photo. According to Todd, the Aug 9 opening just happened with no fanfare at all. The Aug 12 opening, however, was announced, at least to the press. This photog was probably working either for Disney or for some local media outlet.
If you add it up, the most likely conclusion is that this is a scarce relic, an opening day photo from August 12, 1969.