More companies are issuing recalls on Sony batteries lately, as more defects continue to be found. Most recently, IBM and and Lenovo are recalling a total of around 526,000 battery units, due to issues with overheating and potential fire issues, as we've all heard so much about recently. Affected models included the T43, T43p and T90 Thinkpads, as well as others including many in the R and X series. This all comes amidst Sony promising answers and saying they will come up with a battery replacement program:

As Sony announced discussions for the replacement plan the day after IBM and Lenovo announced recalled another batch of rechargeable lithium-ion batteries made by Sony.
With the cost of laptop batteries as high as $200, this fiasco must be costing Sony incredible amounts. Considering that different types of manufacturing defects are to blame, it seems logical to conclude that there is or was a serious flaw in the manufacturing process of these batteries, or perhaps their original design.