I found this presentation by Matthew Hodgson a great overview of the ways "government 2.0" tactics are succeeding at home and abroad. Check out some of his screenshot examples online: FutureMelbourne (a wiki for citizens to design a better Melbourne), Powerhouse Museum (a Sydney museum that allows users improve its online collections through tagging, ranking and sharing information), and Bang the Table (a service facilitating public policy discussion).

Government 2.0 - Trends and adoption strategies - WSG Web Standards Group - Nov 2008