In iOS SQLite is part of the Core Services and you can easily integrate it in your applications.
Even in Android you have access to this platform.
If you don’t know what SQ Lite this is a quote from www.sqlite.org:
“SQLite is a software library that implements a self-contained, serverless, zero-configuration,transactional SQL database engine. SQLite is the most widely deployed SQL database engine in the world. The source code for SQLite is in the public domain.“
So what is your equivalent in WP7. Well if you want to wait the Mango Release of Windows Phone 7
will include Sql Server Compact Edition, so that will provide a fairly good and supported platform, but
in the meantime I recommend that you check http://wp7sqlite.codeplex.com/
