Hello all, your friendly Ozblogistan Tyrant here, abusing my multisite posting powers.
This morning I received two independent reports of trojan warnings being given for two different Ozblogistan websites.
After investigation, I have determined that the server was automatically compromised, presumably by a brand new attack (since we just 2 days ago updated to WordPress 3.4.1), and a trojan inserted into various parts of WordPress.
I have identified and replaced the affected files with clean copies, and you should see no more warnings.
Those who want the gruesome details can learn more.