Just for the record really, but am reading The Groundswell by Charlene Li and Josh Bernoff from Forrester. They accompany the book with a website which includes a profile tool. For this to make sense you need to understand their “Social Technographics®” classifications which describe: Inactives, Spectators, Joiners, Collectors, Critics, and Creators.
Their profile tool includes data for the UK from 2008, and provides the following slices organised by age group.
Data from Forrester Research Technographics® surveys, 2008.