Nobody seems really too sure at what speed the Tualatin, or Coppermine-T will be introduced.
The current i815(E/P) cannot support the Tualatin, nor will current motherboards. As is currently stands, the i815EG or i815B chipsets will support the Tualatin, probably combined with the new VRM version 9.0. Current Coppermines use VRM 8.4.