After rampant speculation earlier in the week, late today PayPal officially introduced the "PayPal Plug-In" - describing it as "a free download for your Internet browser that allows you to pay with PayPal anywhere MasterCard is accepted online."

In addition to generating a unique one-time use MasterCard number for an online purchase, the plug-in also handles autofill of billing and shipping details as well as providing an easy way for you to save a receipt of the purchase.

The plug-in is currently available for PayPal's U.S. customers and can be downloaded at https://www.paypal.com/paypalplug-in.