In Visual Studio 2010, Database Edition or DBPro Projects (.dbproj) have replaced the old Database Projects (.dbp) from previous versions of Visual Studio. Database Projects (.dbproj) are available in Professional, Premium, and Ultimate versions of Visual Studio.
For those who have used the old .dbp projects and have these in their solutions your .dbp projects will be upgraded to .dbproj projects when you upgrade the solution to 2010. If you need help getting started working with the .dbproj project you can find the root node of the product documentation here on MSDN.
Additionally, Deborah Kurata, a Visual Basic MVP, has recently posted a series that provides a gentle introduction into the Offline Database Project environment. You can check them out below.