It seems that many conservationists, artists, and writers have been collaborating and working to mark this centennial with books, projects, and other initiatives to raise awareness of the enormity of this loss and the still-present danger of human-caused extinction. A few links to check out for those interested:
Project Passenger Pigeon - a resource for information, books, and artwork about the Passenger Pigeon
The Lost Bird Project - a film and book project about several species of extinct North American birds
Fold The Flock - an origami-centered initiative to raise awareness about the Passenger Pigeon, tied into the Lost Bird Project
I've worked with Passenger Pigeons as a subject for a few of my pieces, and will actually be involved in a book being published later this year by artist, writer, and collector Errol Fuller. More on that later this year!
Here's a detail of my 2010 project, kapliczek, that features a shrine of Passenger Pigeons installed at the WWII War Memorial near my house.
detail of zaginąć (to disappear without a trace)