VR-Zone has a copy of a note sent by NVIDIA to partners:
NVIDIA is committed to providing our customers with quality products that push the edge of technology and also continuously improve product quality and reliability. To help improve the product quality and ensure smooth and uninterrupted product supply during the current “end stage” of life cycle, NVIDIA strongly recommends that customers transition to this latest revision of the NB8E-SET GPUs as soon as possible. These latest revision units utilize “Hitachi” underfill packaging material that improves product quality and enhances operating life by improved thermal cycling reliability.
This newer underfill material is already being used on 9400M GPUs found in Apple and Toshiba notebooks.
When news of this issue broke I was contacted by an individual with intimate knowledge of the GPU manufacturing process who told me at the time that a true fix would take months and would likely involve new underfill material.
There's been no comment from NVIDIA regarding this memo leak, but in the past the company has been keen to point out that the thermal issues weren't very widespread and that only a limited number of GPUs were affected.