Apple's annual developer conference in San Francisco.
Apple Trademarks 'Mac Pro'
The November 18th 2005 filing categorizes "Mac Pro" under the classification:
computers; computer hardware; computer software; computer peripherals; notebook computers; laptop computers; tablet computers; computer servers; handheld computers; mobile computers; hard drives; audio speakers; speakers for computers; radios; cameras; video cameras; telephones; mobile telephones; personal digital assistants; electronic organizers; electronic notepads; magnetic data carriers; telephones; mobile phones; computer gaming machines; microprocessors; memories boards; monitors; displays; keyboards; computer input devices; computer cables; modems; printers; parts and accessories for all the aforesaid goods
Apple surprised many in January by rebranding the PowerBook under the name "MacBook Pro". Comments by jobs indicated that Apple wanted to use the "Mac" name in their products and that they were also moving away from the "Power" moniker.
Speculation pointed towards the iBook being renamed as the "MacBook", but this trademark might suggest that Apple was considering replacing "PowerMac" with "Mac Pro".