It's really not that uncommon; sometimes whoever makes the batteries screws up and makes a bad batch. Unlike some components, Apple and other manufacturers probably don't have any good way to check that they're going to have an abnormally high failure rate until they've already sold a few hundred thousand of them. It's not like they can dismantle the battery and say "Ooh, this is a bad design, it's going to have an 8% failure rate." or something.
Dell has had
several battery recalls in the past few years--in 2005, 2001, and 2000. HP has likewise had
two battery recalls in the past couple years, one this year and one last year. The recent HP recall, at least, was in response to several batteries actually causing damage and at least one actual injury.
This one doesn't even appear to be a full recall; if it was, they would be saying "Stop using the battery and get a replacement now." You'll note that the Apple page explicitly says it's not a safety risk, just that they're not performing well (probably an abnormal failure rate, but the failures aren't catastrophic enough to be a hazzard). They're probably doing it to prevent bad press about annoying failures, but it's also the right thing to do if the batteries aren't up to spec.
Batteries are just like that. Apple is so high profile they draw more attention with things like this, but it's hardly uncommon in the industry.
