In Visual Studio 2010 DBP projects (also known as database projects) have been replaced by DBPROJ projects (aka SQL Server 2005 or 2008 Database Projects). DBPROJ projects have only been available in Visual Studio Team System 2005 and 2008. Now these project types are available in Visual Studio 2010 Professional, Premium and Ultimate editions.
How do I migrate my DBP projects to Visual Studio 2010?
Refer to this blog post for a tool that will automatically convert your project into a DBPROJ project: Converting .dbp files to .dbproj files
Refer to this MSDN documentation for detailed instructions on doing the conversion by hand: http://msdn.microsoft.com/en-us/library/ee517378(VS.100).aspx