To manufacture a G5 PowerBook poses significant technical challenges, Apple warned again last night.

Speaking during the company's financial call, Apple chief financial officer Peter Oppenheimer called it the "mother of thermal challenges".

Apple has warned of a wait for the last 18 months, beginning in September 2003 when Jon Rubinstein, then Apple's senior vice president of hardware engineering, spoke to Macworld UK, conceding that the possibility of a G5 PowerBook was simply “an issue of good, solid engineering”.

In November 2003, David Russell director of product marketing for portables and wireless at Apple warned: "We certainly want to (make a G5 PowerBook). But it's going to be a while."

Apple warned users once again in September 2004, when Apple's vice president of product marketing, Greg Joswiak, said: "The challenges of cooling a G5 in a PowerBook are significantly greater."

Also that month, Tom Boger, director of worldwide product marketing, warned consumers not to hold their breath: "You're not going to see a G5 in a laptop anytime soon."