SharePoint Shared Services became deprecated in SharePoint 2010, and instead we have new Services architecture, where all services are independent from each other. Such architecture affected the way information and configuration are stored and each services has it's own database.
Previously, with SharePoint 2007 we had at least 6 databases for each installation
With SharePoint 2010 model we still have Central Administration and other databases, but instead of point 3 we end up with the separate database for each Service, for example [Access Services], [Metadata Services], [WebAnalytics Reporting] and etc.
User Profiles use 3 databases: [Profiles] - for the actual profile content, [Synchronization] to keep configurations of the external data and [Social Tagging] to store tags and noted created by users.
This model describes the SQL Server databases that are integral to SharePoint 2010 Products. The databases used in a specific environment are determined by the product, version, edition, and features that are running.
Databases that support SharePoint 2010 Products
Will try to cover some additional details regarding the databases used in SharePoint 2010 in upcoming posts.