Doesn't actually make sense
The thing that annoys me is that I just don't get why apple haven't already upgrade the imac - at the WWDC conference for example.
If what is ben said about retina is true, i.e. to get to 21 - 27' retina displays is perhaps not that realistic right now then surely we can assume the new imacs won't have retina displays. Then if this is the case all that apple needed to do is shove in the new ivy bridge chips, make them 8gig RAM standard, update the graphics cards and maybe offer SSDs as a more expensive option. Essentially just a minor spec bump.
Sure maybe apple have a decent amount of imacs still available in stock that they want to shift but from i gathered when i spoke to a woman in the apple store last week, that shouldn't have been a problem. When the 17 inch macbook got canned last month apple stores had to immediately return all unsold 17 inchers to HQ to be pulled apart and have their parts reused.
If the imac was to have just a small spec bump then surely it would be quite easy to recycl some of the older imacs that havent been sold.
I guess this all unfortunately does give a bit of credence to the October Retina rumour that has just started flying around. Perhaps retina really is sooner than originally thought and therefore, this is the reason apple hasn't bothered to just release a minor spec bump.