Hillary Clinton is going to campaign until the end, and the Democratic Party processes make that not only possible for her, but the logical thing to do.
Neither Obama or Clinton will lock up the nomination solely based on elected delegates. Either one of them needs super delegates to select them in order to secure the nomination. Therefore, an election campaign to win the hearts and minds of the super delegates is now underway. The outcome of this 'election' is unclear at this point.
So why on earth would Hillary Clinton concede and drop out of the race at this point, as so many whiny, petulant Obama supporters are screeching for her to do? It makes utterly no sense, given the reality of the Democratic nominating process.
Again, whoever is the nominee will be depending on super delegates. The super delegates are still uncommitted in numbers that can affect the outcome. The race, as it should, goes on.