The likes of data.gov.uk and data.gov are keen to build a community around their data. How should that best be done?

The main benefit seems to build feedback loop, encouraging use of the data and release of the data. Specifically, these sorts of activities are what users and government might want:

• Users to share:
  • tips for wrangling the data
  • known issues with the metadata and data
  • apps, visualisations & articles related to the dataset
• Government to:
  • respond to questions about the data
  • get feedback about what data is useful and where to improve

Assuming there was budget to try and achieve these things, what would be the most effective way for government to do something? Comments on each dataset page? Host a forum? Twitter? Independent forums e.g. this one? All of these or just one?

Disclaimer: I'm involved in data.gov.uk