Why there is no quad-core
If you check the specs on the processors, the i7-720M and i7-820M (the two quad-core mobile versions excluding the extreme line) do not support Intel HD Graphics. This, regardless of heat issues and battery life, would exclude them from the MBP as it would negate the automatic graphics switching feature.
http://www.intel.com/products/processor/corei7/mobile/specifications.htm
And upon further research, it appears the extreme edition (i7-920XM) does not support Intel HD Graphics either.
http://www.intel.com/products/processor/corei7ee/mobile/specifications.htm
So it looks like the blame is on Intel for now.
If you check the specs on the processors, the i7-720M and i7-820M (the two quad-core mobile versions excluding the extreme line) do not support Intel HD Graphics. This, regardless of heat issues and battery life, would exclude them from the MBP as it would negate the automatic graphics switching feature.
http://www.intel.com/products/processor/corei7/mobile/specifications.htm
And upon further research, it appears the extreme edition (i7-920XM) does not support Intel HD Graphics either.
http://www.intel.com/products/processor/corei7ee/mobile/specifications.htm
So it looks like the blame is on Intel for now.