MSDN has made available a SQL Server 2008 whitepaper: An Introduction to New T-SQL Programmability Features in SQL Server 2008

Summary: This paper introduces key new Transact-SQL programmability features in Microsoft SQL Server 2008 as well as SQL/Common Language Runtime (CLR) enhancements. New Transact-SQL features provide improved performance, increased functionality, and enhanced globalization support. Transact-SQL programmability enhancements in SQL Server 2008 address the needs of both OLTP and data warehouse environments.

This paper covers the following key new features

Declaring and initializing variables

Compound assignment operators

Table value constructor support through the VALUES clause

Enhancements to the CONVERT function

New date and time data types and functions

Large UDTs

The HIERARCHYID data type

Table types and table-valued parameters

The MERGE statement, grouping sets enhancements

DDL trigger enhancements

Sparse columns

Filtered indexes

Large CLR user-defined aggregates

Multi-input CLR user-defined aggregates

The ORDER option for CLR table-valued functions

Object dependencies

Change data capture

Collation alignment with Microsoft® Windows®

Deprecation

Go to the link below and get started!
http://msdn.microsoft.com/en-gb/library/cc721270(SQL.100).aspx