Paypal have owned the domain since 1993 (or earlier) but few people knew it because seems Paypal never gotten good idea to use it.
Recently PayPal announced Paypal “will become the first and only global payments platform open to third-party developers”. their “new set of APIs will offer unlimited possibilities for (developer) to easily monetize (developer’s) ideas, by providing security and connectivity to the world’s financial systems.”

Paypal will move towards the public launch this fall. The team is currently using as their blog to note somethings regularly.

Related links:
news about paypal’s platform