In an update to our story earlier covering Dell's laptop battery recall, it seems that Sony is going to assist Dell and cover some of the cost involved in it. The recall, which affects over 4 million batteries, is heavily in Sony's hands since they were the manufacturer of the affected units. Apparently, Sony also provided other retailers with the same battery, meaning other companies could be affected as well:

The financial impact on both companies is unclear. Sony would not say how much money was involved, but did say it had also provided the battery cells to other PC manufacturers.
While Sony maintains that the percentage of affected units is very low, it is in both their and Dell's best interest to replace all the batteries, since it only takes one unfortunate circumstance to end up with a house burned down or someone seriously injured.