When you create a new C# project in Visual Studio, the generated AssemblyInfo.cs file includes an attribute specifying an assembly GUID. The comment above the attribute stat
Nope, no real reason to include it. It's really pretty unnecessary except in very specific COM interop scenarios. Though I suppose there could be something useful about having a GUID that you can access with reflection. But since it's not guaranteed to be there, its not like you could rely on it.