When I wrote a post on Owen Pallett (a.k.a. Final Fantasy), some of our commenters thought I should have called his music "indie rock" instead of post-rock. Which brings up the interesting question, what exactly is post-rock? Is it a genre, with specific musical conventions and characteristics that can be invoked or withheld for expressive effect? Is it a scene, a regional filiation of bands and individuals? Maybe, and maybe. But I like to use it as a term for music conceived within a particular historical moment -- a moment where the rock narrative is revealed to be the rockist narrative, i.e., as just another ideology, and as such something with a history and therefore doomed to eventual senescence and death.
That, ladies and gents, is the post-rock moment right there. It's not as if you can't make rock music after that awful moment where the jazz-flute abyss opens before you, but you can't carry on as before. Henceforth, you're not rocking, you're "rocking." You take your first tottering steps towards modernism, doubt, and self-reflexivity -- all notably un-rocking things. Incitpit Sufjan Stevens.