I saw this article referenced over at Pandagon and thought it was kind of entertaining (although I do agree with Pandagon's assertion that there was no need to try and turn this into a gender issue).
Personally, I've never broken up with someone over their taste in books or anything, preferring to be grateful that the guy actually read books, some of which were slighlty intellectual on occasion, but maybe I should start taking literary tastes into account more. Also, I have no problem with some of the authors mentioned per se, but if that's all you read, that's a problem - go ahead and read and enjoy The DaVinci Code as long as it's only a small percentage of your overall reading (I read crap but feel I read enough good literature to balance it out) - if that's all you read, though, that might be an issue (or at least, you might feel condescended to whenever your taste in books comes up).
My last ex listed Hemingway as his favorite author and read a lot of James Patterson. He was also into French literature (I bought him Les Miserables in French but he never finished it; he also claimed that Shakespeare's French contemporaries were much better playwrights) - I probably should have seen that one wasn't going anywhere. I'm very much into American literature, read James Patterson in high school but really didn't think he distinguished himself from anyone else in that genre (also read some Jeffrey Deaver and Patricia Cornwell back then, but always intermixed with other literature), and I haven't touched Hemingway since high school (I liked The Sun Also Rises a lot; For Whom The Bell Tolls not so much). I should probably give him credit, though, since he read The Female Thing after I gave it to him - at least he tried.
I can't remember what the ex before that read, though I know he read - some sci-fi, and also philosophy (boring). Basically, his collection was a lot more random, but he was rather snobbish about it.
Pajiba had this to say about movie tastes and dating a while back - I wish they would do a column about books and what that says about relationships because their "Guide to Third-Date Flicks" was very amusing.