[silverdrake11]

It's more plausible to me that the movie was a product of its times rather than the cause of the trend. Maybe there was more interest in wine during that time, and more discussion about the different types. It would explain why a movie centered around wine was developed and became a box office success.

[Beldin]

Sideways is about wine roughly as much as Fight Club is about grown men fighting each other in a club.

[robocat]

The book Sideways by Rex Pickett was released in 2004, and obviously written before that.

Presumably the rant against Merlot is in the book, so perhaps it is less likely to just be a product of the times.