A fault in the batteries can cause cells to overheat, posing a fire risk. Apple has said that it has only had four incidents reported to it, and that no injuries have been caused, however it is duty bound to recall the batteries immediately.
Faulty batteries will contain cells manufactured only during the last week of December 2003. They all have the model number A1045 and have serial numbers that begin with HQ404, HQ405, HQ406, HQ407 or HQ408.
Customers who are concerned that they might have a defective battery can call Apple at (800) 275-2273 between 8 a.m. and 8 p.m. Central time Monday through Sunday. Alternatively, a recall can be arranged through the company's website, here.