When Apple released iTunes 10 yesterday, along with iTunes Ping, a social network for music, hundreds of thousands of users jumped onto Ping instantly, to be greeted with a "Connect with Facebook" button. Connect with Facebook allows you to use your Facebook login information, instead of Apple's ID.
The feature was removed within the first few hours of Ping availability, following several user reports of it not working. All Things D is now reporting that the reason Facebook Connect is no longer present on Ping is because Apple used the feature, despite being unauthorized to.
They are reporting that Facebook has denied Apple the use of its Facebook Connect API's, mainly due to security issues and performance. The two companies were unable to reach an agreement, but Apple still placed the button on Ping.
According to sources familiar with Facebook's platform, the social networking giant essentially denied Apple's Ping access to application programming interfaces that would allow it to search for an iTunes user's friends on Facebook who also had signed up for Ping.
Normally, this API access is open and does not require permission.
That is, unless some entity wants to access it a lot. In that case, Facebook requires an agreement for reasons primarily centered on protection of Facebook user data and, of course, infrastructure impact.
With 160 million iTunes users, that could mean a possibility of a lot of impact.
The feature was never working since Facebook blocked Apple's access to it, and Apple then decided to remove the button.
According to the report, Facebook and Apple remain in discussion regarding bringing back Facebook Connect functionalities to Ping.
[...] Facebook blocked Apple from using the service on Ping and Apple removed the feature.It was later reported that Apple and Facebook were unable to reach an agreement over the API’s for Facebook Connect [...]