Just came across this article:
Beware Counterfeit Memory Cards Being Shipped From Amazon Warehouses (http://www.petapixel.com/2012/12/09/beware-counterfeit-memory-cards-being-shipped-from-amazon-warehouses/)

URL updated... please don't use "shortcut" links on this site.

That story is nothing new; memory card fraud from dubious third-party online sellers has been going on for several years. Unfortunately some of these unscrupulous sellers have worked their way in to the Amazon network. As pointed out in that article, the way to avoid being cheated is to make sure that your memory card purchase on Amazon actually states "ships from and sold by Amazon.com."