Dan said at one stage last night that he hadn't said anything about his 'secret' as he did't want to be seen as coming in the house just to promote it. I know he sings with a band called 'Icehouse' and they have had moderate success in the past so I presume he's talking about this.
Here are a couple of pics of Dan performing at 'Feel the Noise' in 2002.
and
HERE'S A LINK to an article that mentions them.