[rounak]

Twitter and Facebook also have similar solutions. Have they been shut down too?

[ceejayoz]

Twitter and Facebook have extensive OS level integrations put together by Apple.

[pyre]

"Too big to fail"

[jwegan]

I think at least Facebook's usage would fall under the category of facilitating inter-app communication. They just communicate with almost every app out there.

[wnevets]

Wouldn't be surprised if they pay for the privilege.