With all of the good stuff that is going to be part of VS2005, VSS can be overlooked. you can find the roadmap for VSS, here.
In relation to the new features that are going to be in VSS2005, here is a extract from here:
To coincide with the release of Visual Studio 2005, Microsoft will offer Visual SourceSafe 2005, a more highly refined and integrated version control system that adds new and expanded capabilities for teams and individuals. Following minor changes in Visual SourceSafe 6.0d (released with Visual Studio .NET 2003), Microsoft is making more enhancements for Visual SourceSafe 2005. These fundamental changes will improve the reliability, scalability, performance, and remote access capabilities of Visual SourceSafe.
Software efforts that are increasingly global in nature span time zones, domains, and continents. Visual SourceSafe 2005 is changing to address the needs of these global teams:
Teams can take advantage of new automation and extensibility features to automate their processes and extend the functionality of Visual SourceSafe:
Visual Studio source control integration for Visual SourceSafe was updated to improve developer productivity, particularly when developing Web services and Web sites: