From now on, if anyone says that there is a client-side database for Windows Phone 7 like SQL Server Compact Edition, SQLite and so on, he/she will be very wrong.
McObject's open source, object-oriented embedded database software Perst now supports Windows Phone 7.
This is a result of the work of Andy Wigley, a Microsoft MVP
and principal of U.K. consulting APPA Mundi firm.
Wigley is successfully using Perst in the WP7 emulator and looks forward
to working with it on WP7 phones when they become available to
developers later this summer. He expects to see excellent performance,
because in tests against other mobile databases on Windows, Perst “blew
them out of the water,” he said.
You can see the full story here. You may also want to download the Perst database from here and the Windows Phone 7 demo from
here.