They have been doing these screens since 2009 all the sudden lamination issues ? Think about it rationally. I think well see Mac minis and I macs then. They are definitely making a new design there have been many reports to with stating this therefore they will announce it at an even. If not then, then I don't spect the, this year. If there weren't going to re design they would have been out by now. I very confident, even if macs and iOS don't mix apple hasn't been doing logical stuff lately so I wouldn't be surprise by anything they would do this days. Just think about it for a second. Apple intended the iMacs to be done buy July but since those issues they have been force to wait and what better way to go with a boom on that event. Tim cook said it. That they have great products coming down the pipeline I think well see our 2012 iMac then.
They haven't been doing laminated iMac screens since 2009. Doing it with a 27" display is much different and more difficult than doing it with a 3.5" display.
Also note that they haven't done it with the iPad yet, it would probably be troublesome to do it on that size screen at such a high volume at this point. Doing it on the iMac this year might be more feasible because it is a lower volume product.
I just don't see Apple taking time in an event about two potentially huge selling devices, the iPhone and the iPad mini, to talk about the iMac. Either the iMac would take away from the iPhone/iPad announcement, or the iMac will be forgotten by the press because of the iPhone/iPad announcement that followed it.
Even the RMBP, which was a huge redesign, got only a few minutes stage time at Apple's longest keynote of the year. If that huge WWDC keynote only managed 3 topics, Macbooks, OSX, and iOS, then how do you expect them to squeeze that many things into one of their smaller product launch events?
It makes much more sense to give iMacs their own press time on a different week. It will get plenty of press and attention (if it's a major change) even if it doesn't get its own event or stagetime at another event.
I'm not trying to be negative, just don't get your hopes up. People always get their hopes up way too high for Apple's events. When they don't announce every one of the 20 things people wanted to see during a 1.5 hour keynote the forum threads are full of comments about how people are 'disappointed'.