It was 7.5 months between the previous and the update before that, not six. Buyer's Guide includes all iMacs since 2003. Ignore older than 2006 iMacs as those are PPC. It has taken 11 months TWICE since Intel iMacs, and three times it has taken 7-8 months. So, 11 months is not extraordinary, it's completely normal. Whether this update takes 10 or 11 months, nobody knows. It does look like it's imminent but how imminent? Late August seems possible
Another report. Every time Apple instructs its retailers of a short-term shortage tells them to get rid of their stock, a refresh happened soon after. Lets hope the same thing happens here.
Your right, seems like longer due to the fact I bought at just about every refresh for my business. I buy the best for my workers at the firm but usually the base for my house usually. My wife hates the big screens. She is a accountant and controls all the money.I now have the 27 i5 right now, but will have to make due with a 21.5 during the refresh as the i5 is going back to the office. Women are crazy sometimes.
http://www.engadget.com/2010/07/23/imac-refresh-is-imminent-according-to-reseller-sources/