Shared Services in SharePoint 2010

Shared Service Provider (SSP) in SharePoint 2007 has been replaced by Shared Services in SharePoint 2010. SSP in SharePoint 2007 was confusing and had its share of limitations which SharePoint 2010 seems to solve by introducing Shared Services.

Key differences between SSP and Shared Services

SSP in 2007	Shared Services in 2010
MOSS only	Available in WSS
Different services shared the same db	Services can have its own db
Internal to MOSS	Public APIs to create own Shared Services
Only one application of service	Multiple instances of service allowed
Restricted to the farm	Cross farm support

SharePoint 2010 provides the following Shared Services ( not an exhaustive list )

Access Services : Allows viewing, editing, and interacting with Access databases in a browser.
Business Connectivity Service : Provides read/write access to external data from line-of-business (LOB) systems, Web services, databases, and other external systems. Also available in SharePoint Foundation.
Managed Metadata Service : Provides access to managed taxonomy hierarchies, keywords, social tags and Content Type publishing across site collections.
Secure Store Service : Provides capability to store data (e.g. credential set) securely and associate it to a specific identity or group of identities.
State Service : Provides temporary storage of user session data for Office SharePoint Server components.
Usage and Health data collection : This service collects farm wide usage and health data and provides the ability to view various usage and health reports.
Visio Graphics Service : Enables viewing and refreshing of published Visio diagrams in a web browser.
Web Analytics Service Application : Enable rich insights into web usage patterns by processing and analyzing web analytics data .
Word Conversion Service Application : Provides a framework for performing automated document conversions