This updated, expanded version of The Vertigo Encyclopedia was published by DK in 2008, and featured Who's Who-ish listings for various characters from the Vertigo universe.
I've never actually seen the book, so I can't say what kind of listing The Phantom Stranger got. Apparently there were two types of listings--a full one, with pictures, and a second one that was smaller and featured mostly (if not nothing but) text. I don't know which kind of listing the Stranger got, but he's in there somewhere!
Thanks to your efforts, it turns out IATPS will make it all the way to not only October 31st, but November 1st! We have a couple more pieces of merch, and one weird little thing, all coming to you in the next couple of days!
Update! Courtesy Fantom Stranger MW Gallaher comes the above image from inside this book, which is the listing the Stranger received. MW says he's mentioned on a few other pages, but this is his official entry. Thanks MW!