This is Caspar logging on from Porto Alegre. Beautiful warm sunshine. A fresh breeze coming off the wide wide river. One hundred thousand people or more getting together for the fifth annual alter-globalisation jamboree.
To set the scene, openDemocracy has already published a couple of articles by people who in different ways are close to the forum.
The Argentinian activist Ezequiel Adamovsky has been involved in radical campaigning at the WSF, his native Argentina and beyond for some years. He argues the case for "institutions of a new type"
Vince Madeiros is a Porto Alegre local. He examines how some mainstream English language print media - The Guardian, The Financial Times, The New York Times, The Wall Street Journal - has covered previous social forums here.
So what is the whole thing about? If I knew that I wouldn't be here. For some context you can see what I wrote about last years WSF in Mumbai.
Solana Larsen, James Crabtree and others including me will be logging on with more updates over the coming days.