Will apple hold off an update till the mobile quad core comes out is my question.
Unlikely. Even once Intel releases the chip, Apple will need to engineer it to work in MBPs and iMacs. So I would not expect to see quad-cores in those machines until MacWorld 2009 in January.
So it is more likely to see an interim Penryn update and then the new four-core models (with new form factors?) coming next year.