Yeah ... but this button is making fishing super-easy. I'm really not sure it's a good idea (the iframe is a clever trick, but the interface could very easily be copy/paste in a fishing website. Users would have no way to check if their credit card is stolen by the website).
The usual way that Stripe works is that you enter your cc info on the merchant's site and it gets sent to Stripe via Javascript. The only difference here is that they're packaging it up nicely.
