Henry has started to release his archives!
The first is available as a downloadable iBook on iTunes.
This book can be viewed only on an iPad with iOS 5.
It's only $6 USD - it's big, so it takes a while to download, unless you're on cable modem.
iTunes preview (web) link: http://itunes.apple.com/us/book/henry-chalfants-big-subway/id531594319?mt=11
Info from the linked page:
Henry Chalfant's Big Subway Archive
by Henry Chalfant & Max Hergenrother
Henry Chalfant's Big Graffiti Archive is a work of visual anthropology and one of the seminal documents of American popular culture in the late twentieth century. The original artworks depicted here, which have been the inspiration and guide for thousands of youthful artists around the world, were never able to endure for long before the city cleaned the cars, or the artists' enemies crossed them out. Chalfant's patience and determination in hunting down and capturing these masterpieces with his camera has left the world with a representative cross section of some of the best work by the most talented young artists who painted New York City's subway cars in the seventies and eighties, the golden age of graffiti. A handful of Chalfant's photos have been featured in such books as Subway Art and films like Style Wars. Now for the first time, the entire collection will be made available, released serially over the next year until all 800 trains have been published.