Yes Australia's defamation laws can extend to social media. This was recently confirmed in the NSW District Court case of Mickle v Farley in which a teacher was awarded $105,000 in damages for defamatory tweets by a student.
In order to bring an action for defamation on social media, you will need to prove the same elements as for a traditional defamation action, which are:
1. that there was a comment or photograph that was published;
2. it identified you
3. the comment or photo contained defamatory imputations (ie. things that could potentially harm your reputation); and
4. the defendant is unable to rely on any valid defence (such as truth or fair comment etc).
Your first steps should be to contact Facebook or the administrator of the relevant site and ask them to take the defamatory posts down. You may also be able to bring a law suit for damages. You should seek legal advice if you wish to proceed with such a course.
I agree with Sophea above. You can certainly bring an action against the person who posted these statements/photographs. However, one of the valid defences to defamation is opinion or belief. Therefore, unless the photograph and statement constitution an allegation of fact, then it may be difficult to prove a defamatory statement. Further, the court will look at damage to your reputation. Hence, questions such as whether the Facebook profile was public, whether the statement was public and how many people could have potentially seen it and what likely damage this may bring to your reputation in the present or future will also be considered.