Actually I had already heard about this, and I want to make a Faraday cage using cloth for my credit cards. I might be paranoid, but the geek in me thinks it's just cool to work with metal encoded fabrics. I actually want to build a cage for my server next.
That’s why I’m becoming a bigger and bigger fan of cash - it can’t be traced back to you.
In any case, I remember finding out my brother had a RFID-enabled debit card, so I promptly helped him line the relevant pocket in his wallet with a layer of aluminum foil. Fortunately, I have nothing with an RFID chip in it with personal information besides my passport, and when/if it looks like I’m going to use it, I’m buying one of these: http://www.thinkgeek.com/gadgets/security/910f/ before taking it out of my house.