Graphic novels began to earn literary and even intellectual respect in the 1980s with works such as Art Spiegelman's Maus (a Holocaust tale), around the same time people were being blown away by Watchmen and various Batman reimaginings.
Now, I don't think real cartoonists (or at least mature ones) care about being called graphic novelists and not cartoonists or comics artists. I know professional cartoonists, and they love and are proud of comics and cartoons. The semantic battle over graphic novels as a term really just involves communicating with the non-comics folks who look down upon anything illustrated (but whose reading list usually is filled with hackwork airport books and crap self-help tomes).
That said, there's a new generation or two of long-form comics -- erk, graphic novels -- that are evolving this storytelling form in cool new ways. People who are interested in this topic might want to check out the video below of a recent panel discussion in San Francisco featuring some comics heroes.