Technically speaking, C# does not have optionals so I don't think it can be argued that C# violates the patent unless it's generalized to include null propagation which operates on reference types.
The only special sauce I can think of is that C# also implements null-lifting for most operators in the language, which is not necessarily a good thing because it treats null as "unknown" rather than "missing" - e.g. a + b works on int?, and will produce null if either a or b is null. With Boolean operators, it's even clearer - false & null is false, true | null is true, but true & null is null, and false | null is null. But quite often this is not what I actually want! If null really means that the value is missing, then a + b shouldn't even compile for optionals. But in practice, I'd say that vast majority of all uses of Nullable are to denote missing rather than indeterminate values.