[Pseudoscience-is-malarkey (OP)]

...or is their attraction to it something else entirely?

[paul cotter]

That is a good question. I have observed the effects closely and I cannot come to definite conclusion. The effect appears almost instantaneously which would rule out an intoxication as there is no time for absorption. On the other hand their behaviour is often quite radically changed such as a docile cat becoming aggressive. They roll in it, eat it and seemingly enter a state of ecstasy. These effects last about 10mins after which the effects seem to wear off and the cat loses interest in any more exposure and generally putting more out is largely ignored. I am baffled by what I have observed.   

[Bored chemist]

The effect appears almost instantaneously which would rule out an intoxication as there is no time for absorption.

Ever seen someone smoke a cigarette?

[paul cotter]

I think crack would be a better example. Of course I have seen cigar smoking but I have never seen a state of ecstasy develop subsequently like happens with cats and catnip. Even crack would take the time of circulation, lungs-heart-brain, i'm guessing 5-10seconds. With cats and catnip it seems instantaneous. BC, have you ever witnessed this effect?

[Bored chemist]

For experienced users at least part of the effect is psychosomatic.