"My legs literally turned to jelly", "You are up against the Norwegians, who are literally born on skis" and "This album is literally flying off the shelves" were just three of the examples in a piece on Radio 4's Today earlier this week (listen again for a couple more days by scrolling down to 08:46 here). The subject was considered 'news' because Nick Clegg, the deputy prime minister, had talked of people who paid low rates of tax as being "literally in a different galaxy".
Mark Forsyth, author of The Etymologicon, reminded listeners that today's current sense of 'literally' (ie not literally at all) dates back to 1769. The word has its origin in the Latin for 'letter', so the original meaning of 'literally' was (literally) 'letter by letter'. Forsyth said that all words that start off as intensifiers gradually weaken in meaning; he gave the examples of 'probably' which is from the Latin word meaning 'prove' or 'test', and 'quite', which is used in two different senses in English today. 'Quite' can mean the same as 'fairly', but if you say 'quite right' or 'quite the opposite' it still has the sense of 'completely'.
I am rather tardy in following up this story, so the interview will be on the BBC website linked to above only for two or three more days. However, there is a written piece on the BBC website here.