1. Master Data Services
Microsoft SQL server 2008 R2 contains a master data management applications. Master data services have got the following tools.
Master Data Services Configuration Manager. This configuration manager will help you to create and configure master data services databases and web applications Master data services web service. This component is more useful to developers as they would be able to extend or develop custom solutions for master data services Master Data Manager. This is used by users to manage master data
2. PowerPivot for SharePoint
Microsoft SQL Server PowerPivot for SharePoint extends SharePoint 2010 and Excel Services to add server-side processing, collaboration, and document management support for the PowerPivot workbooks that you publish to SharePoint.
3. Multi-Server Administration and Data-Tier Application
Full details of this new feature can be found @Multi-Server Administration
4. Support or 256 logical processors
Support for 256 logical processor is now added in R2 but this requires to be run on Windows 2008 R2. This is a big jump from previous maximum value of 64 processors. Quite a bit jump in my opinion.
5. Support for visualization of geographic spatial data in Reporting Services
Support for reports with visual geographic mapping is now supported in SQL Server 2008 R2.