I’m against QuestionMark for the operator name.
It’s inconsistent with the names for other operators, e.g. Not,Add, Div instead of ExclamationMark, Plus, Minus.
They all have been given names for their intended uses instead of the literal name of the symbol.
Also if, in the future of Rust, we want to add another operator that also uses ? somehow in a different context, then the name “question mark” would carry meaning for two different operators.
Note that this is already the case: * is both used for Mul and Deref, - is both used for Sub and Neg.
Seeing as ? replaces the try! macro, Try seems to me a sensible choice. Or at the very least, some name that makes its intended use obvious.