I've heard about these things. Yes, it *IS* possible that someone, sommewhere, will try to use them for evil, instead of good. But I really don't see this as any kind of threat to privacy.
Exactly what kind of data could someone gain? That you use a particular brand of product? These things cannot acquire extra data. They don't transmit anything. They simply are an ID tag for a particular item.
As well, regulation is to have these devices disabled after a product is purchased as to avoid further use.
Products, virtually all products, already have a 'tag' in them somewhere already. These RFID tags are really just slightly more sophisticated in that an individual item can have a unique identifier to it.
Strongblade! (formerly known as Strongblade!)
"Where are we going? And what am I doing in this handbasket?"