I recently had to create a project with a very long name inside a Visual Studio solution that was stored at a specific path (long also) on the hard drive. When I tried to create the project within Visual Studio 2008 I got an error message saying that the resulting path of the new project would be too long.
The solution I found is a workaround: I created the new project using a different directory base (C:Temp). The project was successfully created and added to the solution this time. I then removed the project from the solution, closed Visual Studio environment, and moved the files from C:Temp to the base directory of the solution (the folder that has a long path string). I opened the solution again using Visual Studio and I used Add Existing Project to add the project to the solution. It worked correctly, and I could then add items, references, and build the project without any side effect.
Maybe this workaround can help somebody else too.