Checklists can be shared with any of your contacts. And if someone is not a contact yet, just invite them!
To share a checklist simply
- select the checklist by clicking on it
- on the right column click on the collaborate icon
- on the popup select the contact you wish to share with
- close the popup
Note that sharing is done on a checklist level and not on a task level. After all, there is no point in sharing part of a groceries checklist!