Neither Apple nor NVIDIA have confirmed this for us. Apparently, many NVIDIA graphics cards are subject to manufacturing defects. As such, they could fail after certain periods of use. I have heard that the supposedly affected 8400 and 8600 cards actually belong to computers built by Dell and HP; Apple may not have them. No one knows if ALL of the chips are bad. Some people say that their NVIDIA-equipped MacBooks are failing, but they are in the minority (so far). Mine works perfectly, and many others do too.
If your MacBook works fine, I wouldn't be concerned. If Apple orders a recall, then it should cover all affected notebooks, covered by AppleCare or not. You can only wait and see.
I have a Macbook Pro with the above mentioned graphics card. There are several stories and a statement from nvidia re a high failure rate? Does anyone have more information? Are all the chips bad? My mac is not coverage by applecare, should I be concerned?