Intel's Centrino has an advantage because they market a separate chip for the thin/light computer... the big, powerful comptuers use P4s or Athlon64s. Apple unifies their line of powerbooks and just uses one chip so the big/powerful 17"er uses the same CPU as the 12" small, light version.
I guess my opinion on the powerbook is that if apple is going to take its sweet time, that's fine, but once it gets here, it needs to be a real competitor, not some low clocked G5. Take the Powermac G5s for example. Apple was so far behind the times with their sily dual 1.42 ghz G4s... Nobody wanted those for performance. HOWEVER... once the G5 came out, apple was a contendor. Let's hope these PBs, whenever they get here, can make it happen.