I don't think school librarians need much convincing about this. My graphic novel section is now front and center in the library, and eats up a good portion of my book budget. There are so many great titles now that even some of the most hesitant teachers are willing to let students read a graphic novel for a book report. The stunning graphic novel version of The Odyssey by Gareth Hinds is just one example of a book that would satisfy any reluctant reader-and his teacher!
This article makes the point that comics and graphic novels can make good reading. I just wish the library bound editions of graphic novels would hold up better to the repeated reading they get!