MacBook Pro battery failure

My MacBook Pro battery died today, swelling up and bursting out of its case. A bit of surfing revealed that this is a common failure mode. Over the past month it had developed the habit of shutting down with no warning and at least 30% battery life remaining. According to the tell-tale indicator lights, it's still OK!

At least it didn't leak or explode... but Apple batteries aren't cheap. Damn.