According to rumors.com the G5 is a multi-core system, with current CPUs stable at Ghz levels, but they also mentioned (look in archives) that there are 1.8Ghz G5s in vevelopment, but rumors states Apple's release plans for the G5 are 1.2Ghz, now if they have 1.8Ghz Max speed now, I think they can get to 2Ghz by the release (probably end of 2002 for holiday season).
Assuming they are 2Ghz imagine all that power (the G5 is 65% faster per Mhz than existing G4s, so think about a 3.3Ghz G4 Quicksilver's power)
On a side note, notice how the MP800 is stable to 867 easy, and the SP867 is stable to 933 easy? This is a classic Apple stratagy, when they need to cut G4 R&D, they just slowly increase the G4's speed until the next big thing is out, thus one can predict the next G4 motherbord at 1Ghz, after at least 2 more sets of Quicksilver G4s anyways.
Assuming they are 2Ghz imagine all that power (the G5 is 65% faster per Mhz than existing G4s, so think about a 3.3Ghz G4 Quicksilver's power)
On a side note, notice how the MP800 is stable to 867 easy, and the SP867 is stable to 933 easy? This is a classic Apple stratagy, when they need to cut G4 R&D, they just slowly increase the G4's speed until the next big thing is out, thus one can predict the next G4 motherbord at 1Ghz, after at least 2 more sets of Quicksilver G4s anyways.
