John J., I'm enough of an elitist to find it a little horrifying that the Time list featured Neal Stephenson and William Gibson -- I've read both books, and they're impressive examples of their genre, but (here comes the stuff that will provoke a million e-mails) science fiction is junk like Judy Blume is junk like comic books are junk.
I will grant you that a great deal of genre fiction is dreck, science and speculative fiction suffer from what novelist Sharyn McCrumb calls the "Bimbos of the Death Sun" curse. That is, no matter how well written and researched, sci-fi inevitably gets slapped with a large chested woman in a tight jumpsuit on the cover art. This leads those who like to act haughty about Lit-rat-chure to dismiss it as "junk". Substitute brass brassieres for fantasy genre fiction, and don't get me started on the largest selling pie in popular fiction, romance novels.
That which the high and mighty lit critics love can also be dreck, but is often presented with the adjective "challenging" or worse, "ground breaking". Sorry, I like a coherent narrative in my fiction and usually a third less (at least) poised angst about the dreariness of life. I am a bibliophile, I love books and can barely part with tattered copies bought for a quarter at the Friends of the Library book sales. Oh how tired I get of people telling me what is worthwhile to read and what is not, what I should read furtively for fear of being labeled a lightweight.
John Miller sensibly defends genre fiction. John Derbyshire tries to but commits his own fallacy (bold mine):
If a great novel is written in the sci-fi idiom, it is at once de-categorized as "sci fi" and re-categorized as "mainstream."
What is "Brave New World," if not sci-fi? You don't see it in sci-fi catalogs, though. Even Vonnegut's sci-fi isn't sci-fi (mostly) -- it's too well thought of (though not by me).
Sci fi is by definition a low category of literature. A really good novel is by definition mainstream... even if it's sci-fi.
And in a way, this is right and just. After all, sci-fi readers aren't looking for high literary merit, and don't want it, or at any rate don't much care whether it's present or not. (Though it is NOT the case that they wouldn't know it if they saw it. Lots of them -- of us -- would. It's just that we don't always want it.) What a sci-fi reader, in sci-fi-reading mode, wants, is, to quote Isaac Asimov, "those crazy ideas." At the heart of every sci-fi story is a really cool idea. "Wow! Just imagine! What if..." If it comes attached to literary excellence, as it occasionally does, that's really neither here not there.
Greatest sci-fi writer of the 20C: Robert A. Heinlein, by a mile.
Recatogorization happens when the haughty lit prognosticators run across a genre book that they can not ignore. It doesn't not magically change the book from whatever genre it is in. Frankenstien, Dracula, and Mask of the Red Death are undeniably horror stories. Your test is to pitch it as a film: picture your book as a movie and chances are it will fall into a genre. If it does not then it is "mainstream" fiction and will rarely be snubbed as "low brow". I agree with Derb about Heinlein, although an admirable case can be made for Bradbury.
The silliness of TIME's list and the Corner discussion stems from that fact that only future generations can determine what becomes classic literature and what get tossed by the wayside. Stephen King will stack besides Shelly, Stoker, and Poe in the annals of classic horror unless I miss my guess, and he is the poster child for pulpy goodness. I am horrified that TIME has snubbed the comedic genius of PG Wodehouse, but I rest easy knowing that his body of work will not wither away for want of a nod by the twiddleheads who have appointed themselves arbitors of literature.