Best site for updates on post-G20 repression is http://arushandapush.blogsome.com/
The Stopg20 collective itself just had people condemn 'Arterial Bloc' and others all over the corporate media and then dissolved, so with any luck we won't be hearing from them.
And finally, while I'm here, those wanting help to kick in instant nostalgia for the stunning radical critiques of anti-G20 events, developed in the lead up to the protests themselves, can enjoy:
http://stopg20.blogsome.com/
http://archive.blogsome.com/2006/10/31/g20-melbourne/
or even http://theoryoftheoffensive.blogsome.com/2006/11/26/draft-notes-on-anti-g20-events-and-aftermath-2/

So the repression continues after the anti-G20 events, including newspapers prominently reproducing many photos of people the cops want to get and inviting the public to assist (see http://www.theage.com.au/photogallery/2007/01/18/1169095898624.html?page=3 and recognise your friends, http://www.melbourne.indymedia.org/news/2007/01/135967.php for some details of arrests). I seem to recall British tabloids running a similar get-the-troublemakers photo display after certain events in Trafalgar Square, with, if I recall, very bad consequences. (Of course the events in question were on a far far grander scale and part of movements of incomparably greater significance, but this is Australia in 2007 and that's what there is.)
Most of the Left apparently believe that 'solidarity' means yelling 'it was them, officer, not me' (see http://arushandapush.blogsome.com/2006/12/28/anti-capitalism-is-the-antis-capitalism-of-idiots-i/, and also http://slackbastard.anarchobase.com/?p=474). Thus it is up to slightly more radical types, really, to start to ask what might be done. Maybe even do it. A fundraiser is organised in Sydney for next Wednesday but so far I know of nothing in Melbourne.
Or maybe I'm just too far out of the relevant loops to know. Anyone?