Hi Mary -
I finally was able to visit the 9/11 Memorial last Tues, along with 3 friends and Robert's picture. The Memorial itself is still just the outdoor part - the massive reflecting pools and newly planted trees. The actual museum will not be open til late fall of 2012, although there is now a small Visitor's Center with video and photographs.
But there didn't seem to be a place to leave his card, until I went inside St. Paul's Chapel across the street. This is where the firefighters and rescue workers took breaks, were fed by volunteers, napped on the pews, received massages, prayer and a listening ear as they worked on the wreckage for weeks and weeks. Then the Chapel became a sort of shrine to 9/11. Although it used to be chock full of banners and messages from around the world, and flyers about those lost ("Has anyone seen Jim Jones? Last seen 9/11/2001 at 8:30 a.m."), it is now an organized memorial spot for those who died. In the northwest corner is a table with photos and small mementos of those lost. I asked a guard nearby if it would be permissible to add a photo to the table of someone who died in Iraq recently, and she said "Certainly."
So here are a couple of pictures of where I left Robert's card. Whether the table will remain as is, or whether they will eventually place all these things inside the museum, I do not know.
In late Sept when I was with my children in Los Angeles, I also gave a card to my son, David, whose friend died in Afghanistan. So you can place Los Angeles on your map, too. And I still have one on Roosevelt Island (part of Manhattan), too.
It's an honor for me to be involved in Robert's journey. May God continue to comfort you and all of Robert's loved ones.