US President Barack Obama (L) laughs with Italy's Prime Minister Silvio Berlusconi (C) and Russia's President Dmitry Medvedev as they pose for a family photograph at the G20 summit at the ExCel centre, in east London April 2, 2009. World leaders are set to declare an end to unfettered capitalism at a G20 summit on Thursday after France and Germany demanded they act fast on promises to prevent a repeat of the worst economic crisis since the 1930s. [Agencies]