RIM has acquired Tungle, a company that specializes in syncing calendars across multiple platforms. RIM has not given any guidance on why they acquired Tungle, but it is interesting that the BlackBerry PlayBook does not have a calendar app of its own. Perhaps RIM is trying to beef up the PlayBook's calendar.
Tungle started as a web app, but also sports iOS and BlackBerry apps. The service allows you to share you calendar across platforms, and on various social networks. It's an interesting concept, and it will be even more interesting to see how RIM uses it for their devices.