Intel announced yesterday that it was having to redesign the Cougar Point chipset that goes with the Sandy Bridge platform. The chipsets are being redesigned and affected units that were already sold will be recalled and repaired. There are a lot of companies that will be having to get machines from customers to get the issue fixed.
The culprit for the degrading IO performance over time has been singled out. Engadget reports that the issue with the chipset comes down to a single transistor on the board that has a higher current leakage than the chipset can tolerate. The issue can apparently also make the SATA port fail completely.
Originally, we had understood that the issue would only degrade performance. It's worth noting that if you are on a board that is affected by this issue that has SATA ports that are controlled by a third party controller, they are not affected.