Exactly. I can only talk about myself, obviously, but I'm looking at the base iMac. The list price is 1158 here in Italy, just as the same day as when it was introduced (if not higher: if I'm not mistaken it was 1149 and it was subsequently raised due to the introduction of a "copyright protection" law or whatever; everything is more expensive here than, say, Germany for that reason.)
I could order a refurb for 979 later today, as soon as they pop on the store again. That's 18% less, almost as if it were VAT free if you will, and most importantly it's below the psychological threshold of 1000. Sure I'd have to add cash to it if I wanted a Magic Trackpad, but instead of "almost 1200" I'd spend "less than 1000". To my eyes it's not so much that it's 179 less, it's the threshold itself that makes me intrigued.
Though that notwithstanding, I can't bring myself to order it. I've been hovering my mouse on "buy now" countless times during the last few months, and never went through with it exactly for the reason you say: the new one may be out next Tuesday, or on the 9th, or sometime during October.
Would my refurb still work? Sure, they don't die just because a new model comes out. Would I be enjoying my new computer? Heck yeah, I'm using a white plastic 2006 iMac right now. So would it be a smart purchase? I don't know, it depends. It'd have a shorter lifespan (OS X would stop being supported at least a year before than if I had just waited a few more weeks for the upcoming model), it wouldn't have USB3, and so on. So am I buying? No. But I'm biting my hands for not having done so weeks or months ago, when it made slightly more sense.