According to information from several colleagues, the month of January will feature the following groups of processors which will all be dual cores :
The 6th and the day before the start of the CES, they will release its new line of mobile CPUs:

You may recall, the X9000 is a Core 2 Extreme while the Txx00 is part of the Core 2 Duo family.
The 20th will be for desktop processors:

The E1200 will be the first dual core Celeron. Given its TDP, it’s likely that it will still be based on a Conroe core (65nm) unlike all the others which are derived from the Wolfdale core (45nm). As for the Yorkfield (a.k.a. quad core Penryns), we’ll have to wait a few more weeks.