Jon Rubinstein, Apple’s senior vice president of hardware engineering, told Macworld UK that the possibility of a PowerBook G5 was simply “an issue of good, solid engineering.” He said, however, that the current crop of G5 processors are designed for desktops, and that a cooler-running version of the processor would be needed for a PowerBook. But Rubinstein did point out that a few years ago, no one thought it would be possible to get a G4 processor in a PowerBook.