1. SQL Server 2008 R2 Parallel Computing Edition

One huge change is the Parallel Computing edition (formerly code-named Madison), essentially the SQL Server equivalent to Windows Server High Performance Computing (HPC) Edition. It will utilize a Massively Parallel Processing (MPP) scale-out architecture to support data warehousing ranging from 10TB to 1+ PB. The Parallel Computing Edition is priced at $57,489 per processor.

2. SQL Server 2008 R2 Datacenter Edition

The biggest change is undoubtedly the new SQL Server 2008 R2 Datacenter Edition. This edition parallels Windows Server Datacenter Edition, and with support from up to 256 logical processors, it's designed to address the highest levels of scalability. The Datacenter edition has no memory limitation and offers support for more than 25 instances. It also will be priced at $57,489 per processor.

3. SQL Server 2008 R2 Enterprise Edition and Developer Edition

The Enterprise edition is the one that’s targeted toward most businesses. With the advent of the new Datacenter edition, the Enterprise edition will be limited to support for 64 logical processors and 25 instances, which really isn’t much of a change. It will be priced at $28,749 per processor or $13,969 per server with 25 CALs. The Developer edition shares the same feature set and is licensed at $50 per developer.

4. SQL Server 2008 R2 Standard Edition

Designed for small and medium businesses, the Standard edition supports up to 4 CPUs and 2TB of RAM, with unlimited database size. It includes support for all BI subsystems including Analysis Services, Integration Services, and Reporting Services, but lacks many of the enterprise-oriented features from the Enterprise edition. It will be priced at $7,499 per processor or $1,849 per server with five CALs.
Related: SQL Server 2008 R2 Appliances

5. SQL Server 2008 R2 Web Edition

This edition is designed to be run by web hosting providers. It provides support for up to 4 CPUs, 2TB of RAM, and unlimited database size. In addition to its relational database engine, SQL Server 2008 R2 Web Edition supports Reporting Services. It's priced at $15 per processor per month.

6. SQL Server 2008 R2 Workgroup Edition

Workgroup edition is designed to provide basic relational database services for departments and branch offices. It supports a maximum of 2 CPUs, 4GB of RAM, and unlimited database size. Its only BI feature is Reporting Services. It's priced at $3,899 or $739 per server including five CALs.

7. SQL Server 2008 R2 Express Edition

Targeted toward developers and ISVs, SQL Server Express Edition comes in three versions. SQL Server 2008 R2 Express provides relational database services; SQL Server 2008 R2 Express with Tools Edition adds SSMS; and SQL Server 2008 R2 Express with Advanced Services adds SSMS and a local instance of Reporting Services. All of the SQL Server 2008 R2 Express editions will continue to be free downloads.