I've been following this thread since the first post and finally decided it was time to add my two cents. Even registered to post a reply
What I've come to gather on rumors and timelines, the situation to me seems to be the following (including a little bit of wishful thinking, obviously...):
iMacs should have been refreshed some time during the summer season, roughly between May and late July. Due to the display lamination issues however, the refresh has been delayed into september/october. Kuos timeline regarding seperate releases of 21,5" and 27" versions didn't feel right to me since the very first moment I had a look at his timeline, so I wasn't surprised when there was no release of the 21,5" iMac with the iPhone event or around that time in September.
It seems, Apple has had display supply issues for every product they have released or planned to release in the last few months. Shortages and low yields wherever one looks, so maybe these issues somehow fall in line with the lamination problems we all read about.
Regarding the stock shortages encountered since around June, this makes perfect sense to me if we keep in mind Apples intention to refresh during the summer months. This is why I believe these shortages do tell that there is a refresh coming; they simply "adjust" to the delay Apple is forced to deal with. Also we have had rumors about supplies shipping some time mid September. If these are to be considered legit, the only reason to not release the refreshed iMacs is - once again - the screen issue.
Of course with the new iPhone "getting in the way" there actually might be another delays with shipping capacities, so we may have to keep that in mind, too.
So my guess is: iMac refresh in mid to late October, as soon as everything is ready and spotlight has moved off the iPhone a little.
Concerning iPad Mini: With new benchmarks of an A6 iPad, I tend to wish that the rumored Ocotber event will not unveil the iPad mini, as it may be released together with the - now how does one have to put it? - "new new iPad" (you folks know what I mean

) in 2013, fitting the annual timeframe. Instead: iMacs, rMPB 13", together with iTunes. This would also give us a nice overall theme for that keynote.
As I said: My two cents, including some wishful thinking
Oh, and one more thing: Its my birthay on October 16th, so come on Apple, bring them iMacs!!
