Apple's update on April 17, 2012 detected and deactivated the Flashback trojan.
Yet two weeks ago I had following the instructions here. After concluding that my Mac is not infected, I disabled Java.
I don't understand how Flashback could have sneaked in, especially after my guard has been up after an Arstechnica article, but that no longer matters.
How do I find out what kind of damage might have already been done? Will one of the log files contain a trace of what has happened?