Amazon aren't trying to shut down all sites that have shopping carts. They wish to shut down the sites that copy them, such as http://www.bn.com which is very similar to them. The CEO of Amazon has said many times that smaller sites or sites that aren't copying them, however the patent was nessecary in order to be able to stop the competition.

So in short, unless you are copying them, don't worry about it
Cheers,
Michael Bray