At first I am sorry, that i don't know, how such software is exactly called.
So let's describe, what i want: A web based software with a secured login area to post some news. This news should be distributed at many different channels (Facebook, Twitter, eMail newsletter, RSS, and so on..) The support of channels should be extensible by plugins. It would be great (not required) if this system is written in PHP and OpenSource.
Thanks very much.