I recently had to determine at runtime the version of the assembly containing a particular type. After some searching I hit upon this:

System.Reflection.Assembly.GetAssembly(typeof(MyNamespace.MyType)).GetName().Version.ToString()

Do note that this will only work if the assembly containing the referenced type is already loaded.

Updated based on a comment, this also does the job equally well:

typeof(MyNamespace.MyType).Assembly.GetName().Version.ToString()

Thank you!