According to Gizmodo the chips were expected to be seen in Jobs' Mob's attempt to make the Pros a little more relevant. The last significant thing he did to his laptops was to give them a unibody design in 2008.
Ivy Bridge was going to help make the laptop superslim using Intel's 22nm 3D "Tri-Gate" Ivy Bridge chipset.
However, according to Swedish website Sweclockers, Intel can't get the chip ready until March or April of next year. This will make it too late to go under the bonnet of any super-thin Macbook Pro refresh.
In fact it would be unlikely to get into production until late December and about two months later for Intel to be ready for a full-scale launch. That would be the quad cores. It would take an extra month before the dual-core models are in the market.
This will be a big disappointment to Apple. It could tout its notebooks as cutting edge as Ivy Bridge chips are expected to deliver a massive 37 percent improvement over Intel's current Sandy Bridge chips. It is expected to cut power usage in half.
Apple had seen that the slim Macbook Air style design was doing well and by shifting the Pro to that sort of look, it might have got a few extra sales.
The late-2010 Macbook Air was popular despite the fact that it had a totally out of date Core 2 Duo chipset. Apple fanboys will always choose style over substance anyway. However Ivy Bridge would have given them graphics and performance too.