Yukon is AMD's Neo platform that should come from HP any day now and some other manufacturers might show it slightly later, sometime in Q2 2009. A bit later comes Congo, a dual-core based refreshed platform to attack some Core 2 Duo notebooks.
The chipset on the new platform is upgraded from 690G to 780G. The Congo platform has a Conesus dual-core CPU and RS780M+SB710 chipset and, of course, 802.11n and 3G support.
Conesus is a new 45nm CPU with 1MB cache and DDR2 support and we are still in the dark about many details of this BGA CPU. Manufacturers are planning to make notebooks based on these dual-cores and they will probably start showing up by Q3 2009 if not earlier.