Discover Card partnered with PayPal to transfer money from a Discover Card account to a PayPal account.

Paying people just got easier! (Inside Discover.com)

This service can be used from a web browser or from the updated free Discover Mobile iPhone app.

Discover Mobile 2.0 (iTunes App Store)

The only information needed to transfer funds is the payee’s email address or mobile phone number. The person receiving the payment needs a valide PayPal account. The person sending money is not charged a fee. An individual receiving the money are not charged a fee either. However, business who receive payment through Money Messenger are charged a fee to accept the money. The person sending the money from their Discover Card account does not need a PayPal account. Those holding Business, Corporate and Titanium cards cannot use Money Messenger at this time.

Discover Card Money Messenger powered by PayPal (Product page)