We are looking at migrating to Visual Studio 2010. Is it possible for some developers to use Visual Studio 2010 and other to use 2008 on the same solution/projects? How will it affect our VSTF builds (VSTF Server 2008)?
once project converted by vs2010 it connot be just opened in vs2008 because vs2010 changes tool version in solution/project files. So you need to maintain two versions of solution/project files.
You will need to have separate solution/project files for 2008 and 2010 as these have different formats - hence the conversion wizard - but you will be able to share other source code files from a common location. Also, bear in mind that you will also have to restrict your target framework to 3.5 or lower to accommodate VS2008.
You only need to have a separate solution file for each version of Visual Studio for this to work. Project files will work on both VS2008 and VS2010 once converted.
What you need to do is to make a copy of your original VS2008 solution file. I find it easiest to give the copy a name that ends in _VS2008.sln to show that this is for VS2008. Once you have your xxx_VS2008.sln file tucked away next to your original sln-file you can open the original and have it converted to VS2010. When done you can rename the converted file to end with _VS2010 so anyone still working in VS2008 won't open it from their recent projects in Visual Studio and wonder what is going on.
We did this when we went from 2005 to 2008 and we are doing the same now when we are going from 2008 to 2010. Worked fine the first time and so far it has been working for VS2010 for almost a week now without any of our developers reporting problems with it.