From The Sydney Morning Herald:
Master Harper of the [Australian Capital Territory] Supreme Court ordered that a default judgement could be served on defendants by notification on Facebook [via the defendants' Facebook accounts].
A default judgement is given by the court where the defendant does not appear in court to defend the case....
Usually [notification about the default judgment to the losing party] is done by way of personal service or the mailing of the judgement to the defendant's home. However, service can be difficult where the defendant is not easily located.
Courts do allow service by way of email and in the recent Sonny Bill Williams and NRL matter, the court made an order for "substituted service" by allowing certain court documents to be served on Sonny Bill by text message to his mobile phone....
Thanks to BNA's Internet Law for the pointer.
UPDATE: Some laugh-out-loud items in the comments to this post; check them out.