A full featured checkout process in your email

The most interesting part of this to me is the swatch - I'm guessing they use some advanced CSS3 techniques to do that, since you presumably wouldn't be able to use JavaScript in email.

That aside, it looks like a pretty straight-forward form submission. No real security concerns - as it posts to a webapp and the credit card is stored server-side. Biggest concern might be that an attacker could buy things for you and they'll ship to your address? All they'd need to know is your billing zipcode (which isn't too secure).

That aside, their best bet would include releasing plugins for popular ecom software - such as Magento.