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Well, then again. A google search on ("powerbook G5" site:www.apple.com) shows 3 typo's of powerbook G4 to powerbook G5. Two on the italian site and one on the french, so probably a translation error.

For the error as mentioned here to occur, both apple needs to misspell G4 and Avenue A/aQuantive needs to misspell G4 on their websites, which is not very likely.
 
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