Recently (well, a few months or even a year ago), my bank, here in Australia, introduced this PayWave technology to their Visa debit cards. They claim it's secure, but all they talk about is their policies, which requires you to notice that there's a problem (From the website):
Visa payWave-enabled cards are backed by Visa's Zero Liability Policy1 and are as secure as any other Visa chip card. They carry the same multiple layers of security, which ensures that you are not responsible for fraudulent or unauthorised transactions.
It obviously doesn't carry the same layers of security, as you don't have to use your PIN or signature. Well, for purchases under $100, but even that is a lot of money to some people (any amount is a lot to me), so it's a bit weird to say that anything under that is a "low-value" purchase for anyone. If a homeless person found/stole my card, I don't see them buying anything above that.
Someone I was talking to even suggested that a person could walk down the street with one of these PayWave machines in their bag, and bump it against other people's bags in the hopes of finding a compatible card.
It sounds like they're sacrificing security for convenience, and underestimating the ingenuity of thieves. I can't seem to find any information that isn't advertising or otherwise biased, and I don't have any expertise in this area at all to tell the difference between a legitimate concern and paranoia. Is Visa PayWave as secure as it claims?