The battery recalls have still not come to an end. Acer has hit a bit of bad luck this year, what with HP coming after them and now a battery recall. Sony is still to blame in this, with them recalling 27,000 units with batteries in them that were manufactured by Sony. Laptops sold from May 2004 to November 2006 are at risk, though not all Acer models use these batteries so not all are at risk. IN particular, they gave a list of affected models:

The laptops possibly containing the recalled batteries were the TravelMate series with 4-digit model numbers beginning with 242, 320, 321, 330, 422, 467, 561, C20, and the Aspire series beginning with model numbers 556, 560, 567, 930, 941, 980.
If you own an Acer laptop, you can also look at the battery itself. Acer is advising anyone with an affected system to stop using the battery altogether and to contact them for a replacement. They have a site posted with more details.