The NYT has a lengthy article on the gaping digital divide between Republican and Democratic campaigning and fund-raising in the 2012 presidential election.
This really says it all:
Romney’s senior strategist, Stuart Stevens, may well be remembered by historians, as one House Republican senior staff member put it to me, “as the last guy to run a presidential campaign who never tweeted.” (“It was raised many times with him,” a senior Romney official told me, “and he was very categorical about not wanting to and not thinking it was worth it.”)