Apple Pay utilising Visa's Tokens technology, which uses a number of different metrics to create a one time authorisation number which is completely single use. So when Apple says the merchant doesn't get to see your credit card number, it really means it.
For those rocking Android phones, Visa has confirmed that this technology will be coming to that platform too, presumably via Google Wallet.
For Mastercard and AMEX customers, there's no detail on whether Visa's solution is used to secure their payments as well, or whether they will be implementing their own technology
There's also still no confirmation that merchants will be able to continue to use existing RFID based PayWave / PayPass contactless readers, however some of the Apple Pay literature suggests that it can be used wherever you see the current contactless logo - which would strongly suggest that this will be the case.
That will be good news, as it will support a much quicker global rollout. Which has to be in everyone's interests, given the improved security it delivers.