The topic tonight was about ending "shape discrimination" and the ad in question that was banned from airing basically compared a fat joke to a gay joke and two racial jokes, with the [intended] takeaway message that fat discrimination is exactly the same as discrimination based on race or sexuality and that all discrimination is ugly and harmful.
You can view the ad by The Foundry on a special site created by The Gruen Transfer's production company, Zapruder, along with a 15 minute panel discussion of the ad only available online - http://www.antiprejudicead.net/landing.asp
The other ad approaches the issue from humour (using the headless fatty footage) and plays it very safe - you can see it on the ABC website here- http://www.abc.net.au/tv/gruentransfer/thepitch.htm
The most interesting part of this is that people will be talking about fat discrimination tomorrow. I honestly never thought it'd happen in Australia this year.