Steam will begin offering discounted bundle prices for gamers who already own titles that are included in the bundle. That's right, if there is a set of games that you are interested in buying, but already own any of the titles, you'll only have to pay for the rest of the ones you don't own. There will be a new 'complete the set' option, allowing you to avoid paying for the same game again.
Full story from the WindowsCentral blog...