A new 17-inch MacBook Pro was announced today at MacWorld. It's thin, lightweight (for a 17-inch notebook), but has one serious flaw: A non-removable battery. No matter how Apple tries to explain how they've been able to make the battery last longer (up to eight hours) using built-in chips, special technology, etc. it's a real limitation. Eight hours likely mean five hours in the real world, like the MacBook Air's five hours was...