When Phil Schiller, Apple's vice president of worldwide product marketing, introduced the company's 17-inch unibody MacBook Pro notebook at Macworld Expo, he spent a good chunk of time talking about the laptop batteries. According to Apple, the MacBook Pro's Lithium-Polymer battery uses sheets of polymer plastic that can be molded into any shape, occupying less space than a traditional Lithium-Ion battery (which typically uses cylindrical cells). Here, the notebook's voltage changes and instead of the notebook charging the battery at a consistent voltage--which can wear down the battery's cells)--the battery incorporates a chip on each battery cell that communicates what voltage is needed. The other result of Apple's engineering feat is that, unlike with the MacBook and 15-inch MacBook Pro, the 17-inch MacBook Pro's battery is not easily removable or user-replaceable--a sticking point with many users. At the Apple booth at Macworld Expo, Wiens said he saw the new MacBook Pro with its back plate removed, and noticed that the battery itself was similar to that being used on the MacBook Air--which he considers easily replaceable. Wiens did admit, however, that the non-removable status of the battery probably wouldn't be a deal-breaker for most users, unless they were involved in travel or projects that required more than eight hours of battery life.