The G20 started with a clash of elegance and fury, a rather apt combination considering it's being held in London. Barack Obama met the Queen, in one of those performances of executive necessity that ultimately means nothing. No disrespect to the Queen, she's a wonderful woman, but one of little significance, and certainly no significance to the G20. Instead of wooing the Queen, Obama should have perhaps spent more time with Sarkozy and Merkel laying down the groundwork for tighter regulation of the finance industry.
But all of that photo-op mush is simply the way things work. Contrasting with that were the estimated 5,000 protesters battling a heavy police presence in London. A combination of environmentalists, aid groups, political activists, economic radicals and pissed-off civilians, they trashed the Royal Bank of Scotland's London headquarters, smashed windows left and right but so far injuries have been relatively minor (though SKY News has footage of one cop being bashed over the head with a giant pole.)
Several days still remain in the summit, so there's plenty of time for things to escalate, but so far things haven't reached the levels of violence that the police expected, or that caused a great number of bank employees to attend work in plain clothes to avoid being associated with their employers.
As for the policy, other than Merkel and Sarkozy's continued joint efforts to institute sweeping reforms and a new nuclear deal between Russia and the US, the only major revelation to come out of today was an unofficial announcement that Obama would be visiting China later this year. Oh, and Gordon Brown mumbled something about his new deal, but no one really listened.