intel Core 2 Duo ("Conroe")
TheRegister has a nice bit of info
about the processor most likely to find its way into the "good" and "better" configurations of the Mac Pro, which is expected to be launched by Apple before or at WWDC in August 2006.
Apparently, intel has hit a very sweet spot both in performance and power-efficiency, something the firm's processors long were very, very bad at. This, of course, is what Steve Jobs has been talking about ever since the move to intel was unveiled at last year's developer conference.
The "best" Mac Pro machine as well as the Xserve line of processors are going to use the "Woodcrest" Core 2 Duo processor, a version of Conroe aimed at the server/workstation market, enabled to be used in pairs and more. (The "Conroe" processor only allows one processor - although dual-core - setups, which is fine for the "good" and "better" Mac Pros, but not enough for the "best" machine, which should easily beat the G5 quad when it arrives.)
The article also mentions "Merom" again, the third part of the Core 2 family, which according to intel will bring 25% more performance with the same energy-consumption at the same clock rate to our iMacs, Mac minis and MacBooks. In addition, the Core 2 family will also bring 64bit extensions to intel's Core line of processors - and for the first time therefore to Apple's notebook lines as well. Apple is currently expected to bring "Merom" to the MacBook Pro line in Autumn and update the MacBook line in January for MWSF.