Today, IBM will be releasing the first computers (RS/6000 servers) to take advantage of a new process called "silicon-on-insulator" (SOI) according to this CNet article. This advance is in addition to Copper chips and the "low-k dielectric" chips announced in April.
"These new chips are expected to run 20 to 30 percent faster and use less power than traditional chips"
Also of interest: "Texas Instruments and Motorola are now considering using SOI technology in future chip development."
Notably absent, though, is any mention of applying this process to PPC chips used by Apple -- but this is an obvious target for both IBM and Motorola.