Actually for a new feature it's decided by the feature freeze date: if the patch is ready (it complies to the coding guidelines, it is complete and tested...) before the date of the feature freeze it will be included in the release, if not it will not. That's the general rule, we could have some exceptions but when we will be in this case we will decide how the decision is made.
About the bug fix version it's up to the release manager to decide if the patch isn't too big yes, but in some case it's very obvious:
- A new event can be included
- A new feature can't be included
- A refactoring can be included
- A major UI change can't be included
For the other cases it could be more difficult and the decision is up to the appreciation of the release manager.
EDIT: I said: "everyone can submit what they want"