This afternoon, my MBP suddenly shut off while I was using it on battery to browse the web. It was at about 38% or so charge, so I didn't think it was the battery that had caused it to die like that. Repeated attempts to get it working again failed, as my MBP shut off either shortly after restarting, or just as OS X was loading up. I figured it might be a hard drive or logic board issue, and called up the Chandler, AZ Apple Store to see if they had any appointments for tonight. They did, and so I went down there, feeling grim about getting my MBP working again. Thankfully, it was a quiet night for the Store and I only waited for a few minutes before the iPod genius, her queue closed for the night, took my case on. Of course, my MBP started up normally, but it turned out that the battery charge was at about 7%. After discussing the case a bit, she took my battery out and examined it. She quickly identified it as a defective battery (with the telltale expansion on it) and gave me a new one free of charge (AppleCare, but still). I got a few other questions answered as well and things seem to be back to normal. That makes two free batteries that I've gotten for my Mac laptops. I was thinking of buying a new one anyway, but no need now! Just wanted to share .