Everything I've seen with respect to Centrino performance has been pretty good, but I think it is a stretch to say that a 2.5GHz G4 is need to compete agaist current gen Centrino/Pentium M machines.
Generally though I'm more concerned about being competitive in the laptop arena. That is good value for the money. If the performance equation becomes to large then eventually a Centrino running Linux becomes a reasonable alternative to a PowerBook.
Originally posted by Existence
Apple needs at least a 2.5GHz G4 to compete. Centrino is much faster than the G4 clock-for-clock and some say even faster than the G5 on a clock-normalized basis. Dothan, Centrino's sucessor will come this summer and have more L2 cache (2MB) and faster clockspeeds (2GHz+). The PowerBooks right now are simply pathetic.