The number one request we have gotten after launch has been about accepting Paypal.com payments. We just launched the ability to pre-fund accounts using Paypal.com directly.
Please note to do this you have to navigate to My Account > My Settings > Billing > Add Funds.
We hope to have Paypal.com payments in the shopping cart in the next few weeks, but for now adding funds will allow people who only use Paypal.com to get in and start using the system!