Thank you for the suggestion, Daniel.
Integration with Active Directory is on the roadmap and will be eventually implemented as well as task ownership indication. For now you can use the annotation field in tasks to indicate the user who created the task.
Also in EM Server 1.3 (released by the end of December) we will be introducing spaces. The spaces allow separating tasks (and files) into isolated views (optionally, password-protected). Such views can be designated to teams of users, or even particular users.