Actually the C# ternary operator isn't equivalent to IIF in VB, because the IIF function always evaluates both the true and false actions, whereas the ?: operator is a lazily evaluated left-associative operator which only associates the appropriate action. e.g. IIf(a IsNot Nothing, a.ToLower(), String.Empty) will throw a NullReferenceException in VB if a is null because it will try to evaluate a.ToLower() anyway, whereas a != null ? a.ToLower() : string.Empty will not throw in C#. The C# ternary operator didn't have an equivalent in VB until VB9, where you can now write the rather confusing If(a IsNot Nothing, a.ToLower(), String.Empty).

Logically it is the same, but it looks like it isn't technically the same (good tip gregbeech)

IIf is evil. Other then the reason mentioned by gregbeech, the other thing is that it returns an Object so in most cases you would need to cast it before assigning the evaluated expression