OfficeTalk lets you mark a task as private. When a task is marked as private, only you can see it. Any other user, who has at least read access to your task list will see the word 'Private' in place of the task's description when they view your task list.
You can mark a task as private in the following way:
Bring up the Task property sheet by clicking on the task using the right mouse button and selecting Edit from the context menu.
Check the Private check box and press OK to save your changes.