To better explain the situation I'll try to do it by example. There is a service on the domain domain.ru on it the user, in most cases, is authorized only through API social networks or OpenID identifier, then creates the event, indicating the friends who should be notified about them and the method of notification.
About the sending messages by SMS and E-mail everything is clear, but how to notify friends of our user so that they are guaranteed learned about the event through social. network?
I know that the applications (in Facebook) can send notifications, but there is too much garbage, and most people simply do not read; on the wall to throw the invitation makes no sense — it's private; access to private messages, nobody will. Keep in mind the fact that the message is not one to go and call frames for each submission will be to kill the whole idea of automation (then there is the issue of protection from spammers).
Any ideas? And how things are going with Facebook and Twitter?