This was my thoughts as well, that there doesn't need to be a further update for the iMac. The current iMac already uses an overclocked Santa Rosa platform that brings 1066MHz FSB and DDR2-800, which is the majority of the benefits of Montevina. The iMac also doesn't need an IGP chipset. There really isn't a pressing need for an immediate update.
Dual processor Nehalem Xeons aren't going to be available until Q1 anyways for the Mac Pro. And the Mac Mini is constantly waffling in its viability. Just like there was a specific iPod event and then a dedicated notebook event, it'll make sense for Apple to have an official dedicated desktop event early next year to incorporate the refreshed iMac and Mac Pro and probably a redesigned Mac Mini or a new replacement product. This may be at Macworld if Snow Leopard doesn't take up all the time, but will probably be later since I don't think the Xeon/Mac Pro will be ready by then. Hopefully, Apple takes the time to plan for the incorporation of next-generation GPUs.
Dual processor Nehalem Xeons aren't going to be available until Q1 anyways for the Mac Pro. And the Mac Mini is constantly waffling in its viability. Just like there was a specific iPod event and then a dedicated notebook event, it'll make sense for Apple to have an official dedicated desktop event early next year to incorporate the refreshed iMac and Mac Pro and probably a redesigned Mac Mini or a new replacement product. This may be at Macworld if Snow Leopard doesn't take up all the time, but will probably be later since I don't think the Xeon/Mac Pro will be ready by then. Hopefully, Apple takes the time to plan for the incorporation of next-generation GPUs.