We are working on an update for Visual SourceSafe 2005 to make it work with VS 2008. We had originally planned to have it available at the same time as VS 2008 downloads went live but we hit a last minute bug that is taking a little time to work out. Our current expectation is that it will be available in mid December 2007.
In the meantime, if you need to use SourceSafe with VS 2008, there is a CTP of the update available - although it requires one manual work around for during installation. If you plan to use VS 2008 with SourceSafe, make sure to pick up the Update CTP from http://www.microsoft.com/downloads/details.aspx?FamilyID=FAF41EDD-924D-449F-AEFC-9C86DD499720&displaylang=en. Without it, some features like "Open from Source Control" will not work at all. Pay close attention to the install instructions as well. As it says in the KB article http://support.microsoft.com/?kbid=939808:
You may receive error messages when you use Visual Studio 2008. This problem occurs because some compatibility fixes require the Tdnamespaceextension.dll file to be reregistered after you install Visual Studio 2008. To reregister the Tdnamespaceextension.dll file, type the following command at the [elevated - RB] command prompt:
regsvr32 "%programfiles%\Microsoft Visual SourceSafe\tdnamespaceextension.dll"
Why does SourceSafe need an update anyway? Aren't VS plugin interfaces supposed to be backwards compatible? Yes, they are. In fact, there are no changes to the MSSCCI API in 2008; none of the fixes are related to MSSCCI. (3rd party source control developers can now breathe a sigh of relief). The changes come from the way SourceSafe implements Open from Source Control, Add to Source Control, and Share inside Visual Studio.
Starting in VSS 2005, these functions let you browse the database inside VS's open/add dialogs instead of hanging off the File -> Source Control menu like most other source control providers. It's a cool trick known as a namespace extension. In VS 2008, as you may have noticed, those open/add dialogs got a facelift: like VSS 2005, VS 2008 now uses the standard Windows dialogs. So Vista users in particular get a spiffy new one with integrated search & everything. Unfortunately, that change broke us pretty badly, leading in one way or another to at least 10 of the bugs on my list. Bottom line, you don't want to be caught without the Update linked above.
Hopefully these fixes demonstrate our commitment to keep SourceSafe 2005 a viable option with VS 2008, Vista, and beyond! Cheers.
Anand..
http://blogs.msdn.com/sandcastle