Nearly everything you save (including tasks) has the option of being made public or private. Unfortunately, there is no way to only make it public for one other person. This may not work for your purposes, but you can make it public just for a moment to share it with another person, and after the other person saves it to their account, you can both make it private again.
We do plan on offering more collaborative options down the road, but I can’t give you a timetable just yet. I’d encourage you to check out our Get Satisfaction page to leave your input! Keep it coming!