If you've been looking for an easy way to integrate a shopping cart kind of application into your site, but don't want to deal with the hassle of installing one of the many packages that are out there (not to mention getting a real merchant account), then this new article from Zend might be just what you need.

To use this Paypal through PHP method, one needs to already have a valid Paypal account and a PHP enabled website. Once you set up the IPN information for your site, you're in the clear. Take a look at the sample code (and database structure) to see if what they have will work for you and your site.

It looks like it's basically a POST request to a specific URL on their (PayPal's) side of things that's specific to your site - making a payment quick and easy for users with Paypal accounts already.