No. But not because we don't want to, we just don't want their marriage to end up in a disaster.
Events can be thought of as rigid individuals, paranoid about punctuality. They're time based, and they won't let go of their favourite sweater.
Tasks, on the other hand, are completely laid back. They have no sense of time, or rather don't care. They'll wake up late, and sleep early. And they'll make you work for them instead.
Can you mix the two? Sure, but only if you're looking for a disaster.
2Do is a Task Manager and thus its primary focus is managing tasks. Tasks, when compared with calendar events, are highly flexible as you may or may not assign a date or time to them. Calendar Events on the other hand, must always have a date or time assigned to them. You cannot, for example, create an Event for which you have no particular date and time in mind. Unless you're an astronaut, "Fly to the Moon" would be best suited as a 'Task' than a Calendar Event. You cannot mix tasks with calendar events. Apps that do this, mostly only do this to demonstrate this very fact. Not only would the app turn into something you no longer want to use, it'll become useless and complicated for the majority of those that understand the two need to be managed separately.
Having said all that, 2Do does still, however, display iCal events in a Calendar Events panel of its own. On the iPad it's immediately visible to the right hand side. On the iPhone, simply swipe the Task list to the left to reveal the Utility Panel, and then tap on the Calendar button at the bottom to bring up your events. This panel is there only to provide you with the bare minimum tools of viewing, adding and editing calendar events. It's not meant to be a replacement of the Calendar app, but is good enough as it allows you to get to your events while you're procrastinating.
This feature is not available on the Mac.