Motorola has increased manufacture of G4 chips to meet Apple's demand - and resolved 'errata' that plagued 500MHz models.

Phil Grove, director of communications and marketing at Motorola's Texas plant said: "Apple had an amazing demand for our product just as we went into production. Motorola is now run-rated to meet Apple's demand in the fourth quarter."

Following the errata remedy, retailers say Apple may have G4 500MHz machines available before Christmas.

Others suggest that the machines are most likely to surface first on the Apple Store.