There's a ton of new stuff in Visual Studio Team System 2008. I've copied the content list from the online help library below, so you can jump directly into the library from here.

Team Foundation

• Team Foundation Build

  • Build Definitions

  • Continuous Integration of Builds

  • Scheduled Builds

  • Build Agents

  • HTTPS and Secure Sockets Layer (SSL) for Build

  • New Properties for Customizing Team Foundation Build

  • New Tasks and Targets for Customizing Team Foundation Build

• Team Foundation Source Control

  • Destroy

  • Get Latest on Check-Out

  • Annotating Files

  • Comparing Folders

• Team Foundation Work Item Tracking

• Team Foundation Server Management

Architecture Edition

• Design Application Systems by Using a Top-Down Approach

• Conform .NET Web Service Endpoints to WSDL Files

• Generate ASP.NET Web Application Projects for ASP.NET Applications

• Save, Import, and Export Custom Prototypes

• Select From Multiple .NET Framework Versions

• Select From Multiple Office Versions

Database Edition

• Specify Table and Index Options

Developer Edition

• Code Analysis

  • Rules Extension and Enhancement

  • Spelling Checker with Custom Dictionary Support

  • Better Control over Suppression from the Error List

  • Auto-Suppress Generated Code Option

  • Code Analysis Policy Improvements

• Code Metrics

• Profiling Tools

  • 64-Bit Support

  • Full Allocation Stacks

  • Line-level Sampling Data

  • Report Noise Reduction

  • Runtime Control

  • Filtered Analysis

  • Compare Reports

  • Improved Chip Counter Support

  • Windows Counter Support

  • Compressed Report Files

  • Hot Path

  • Copy Report View Data to HTML

  • Windows Communications Foundation Support

  • Load and Web Test Integration in Visual Studio Team Suite

Test Edition

• Testing Methods of Your Code

  • Use Unit Tests in Visual Studio Professional Edition

  • Run Unit Tests More Easily

  • Use Inheritance Between Test Classes

  • Run Unit Tests on Devices

  • Create Host Adapters

  • Improved Unit Test Data Binding

• Web Testing Web Sites

  • Call a Web Test From Another Web Test

  • Improved Web Test Data Binding

  • Improved Web Test Features

• Load Testing

  • Control Load Modeling

  • Improved Load Test Analyzer Views

  • Improved Load Test Results Repository Management

  • Published Schema for XML Files

What's New in Visual Studio Team System