I think you are missing the target for collaboration here. Government agencies may draft policies but the Government of the day i.e. the politicians decide the policies. In Australia my primary path to policy decisions is my local member or the appropriate minister; it isn’t a Government department or agency. The politicians are supposed to represent my view and to take the views of their constituents into account when forming policy.
So the questions should be
1.How is Web 2.0 going to help me interact with my representatives in the parliament?
2. How is Web 2.0 going to help me obtain services from Government agencies?