I stumbled over this whilst surfing this evening, and I think its a fantastic idea for those worried about disclosing credit card information online, or in a shop for that matter.
Basically PayPal have teamed up with Visa to offer a sort of pay as you go Credit Card. So you pop £50 for example, and there you go, off spending.
I dont know what would happen if you go over your pre topped up credit, probably be a few issues there 🙂
Read more on PayPals site.