According to this Electronics Weekly article, IBM is about to begin delivering 90nm chips to Apple:
IBM is about to deliver its very first volume production of an SOC on 90nm, said Reeves. This will be a design for Apple.
Unclear is the significance of the "SOC" (System-on-Chip) -- whether this represents any new information, or somehow simply refers to the 970 chip.
The Xserve G5s utilize the 90nm PowerPC 970 and is scheduled to begin shipment in February.