Contactless credit card payment

They are more and more popular.

http://www.ratecreditcards.ca/blog/visa-paywave-and-mastercard-paypass-gaining-popularity/

Are they compatible between the 3 credit card companies? There are dual reader now.

http://www.casauto.com.tw/en/in-products-03.aspx?id=P_00000039&cid=C_00000010&pname=EZPROX&cname=Contactless+Reader

(I am not advertising this product. It is searched from Google)

Are they secure and safe without leaking information over the air? Would the rader scan all your contactless credit cards in your wallet? Someone has already expressed the concerns.

http://www.theregister.co.uk/2006/10/24/rfid_credit_card_hack/

Contactless credit card payment