Naw, nothing earth-shaking there. It was interesting that in the one I quoted the guy does contradict himself multiple times. Ultimately that means of course that he has no clue either which is in keeping with what I've been saying all along - nobody knows.
My guess? Next year when a more substantive upgrade can be made along with plans already to upgrade the Pro line. If you can afford to wait, you are probably better off waiting for 2013 iMacs. If not, I don't think you risk much buying now. For most users ivy-bridge is no big deal. The performance improvement would be negligible. USB 3.0? Do you really care how fast Time Machine backs up in the background while you work? Otherwise, how often really are people moving large amounts of data manually via USB? Sure, some do I suppose but the majority of users? I don't think so. Retina? What are the odds for that in October on a 27" iMac? What GPU will power that adequately for all purposes?
If they do a refresh before the year is out I have a feeling it won't be anything to write home about, especially for those who waited a long time for it. But we'll see. There isn't much time left to wait now.