Last week was a champagne moment for celebrities with an interest in good causes and high politics. Bono, front man of U2, the rock band - one of Time magazine's "Persons of the Year" and a popular Nobel Peace Prize nominee - launched a suite of must-have consumer products and services aimed at raising funds to fight Aids in Africa, including American Express credit cards, Gap T-shirts and Emporio Armani sunglasses. And Kofi Annan, the United Nations secretary-general, spoke in Davos last week of his organisation's determination to engage with "new actors on the international scene", including not only the private sector, media and non-governmental organisations but also "celebrities from the worlds of sport and entertainment".

Famous people have always dabbled in good deeds. But the trend seems to be accelerating in tandem with our galloping fetishisation of celebrity. First-class airport lounges are now crowded with rock-star diplomats, spokesmodels and "actors without borders". Angelina Jolie, "it" girl and goodwill ambassador for the UN High Commissioner for Refugees, recently toured camps in Pakistan with her boyfriend, Brad Pitt. In December, Bob Geldof was appointed a consultant to the Conservative party's policy review on global poverty. Unicef's celebrity supporters include David Beckham, Ricky Martin and Robbie Williams. Fashion designers have not been forgotten: Giorgio Armani is associated with UNHCR and Pierre Cardin with Unesco. The UN Population Fund has no less than five former Miss Universes in its stable of goodwill ambassadors. Michael Douglas is a UN "Messenger for Peace", speaking publicly on the proliferation of small arms, a topic on which he is presumably expert given the number of films in which he has wielded them.