I came across an interesting article from The Sydney Morning Herald in Australia this week entitled "Lawyers to serve notices on Facebook". Basically, a Canberra judge ruled that legal court documents could be served to defendants on their Facebook page when it was reasonable to believe that the pages belonged to the defendants. The defendants could not be contacted in a normal manner, and their "Facebook profiles showed the defendants' dates of birth, email addresses and friend lists and the co-defendants were friends with one another." With this information, the judge allowed legal notices to be served upon the defendants as an alternate method through their Facebook pages.
It will be interesting to see if this is appealed, and if it will be used in other jurisdictions as well.
Previously, in Australia, text message and email have also been used to serve legal notices.