The only option you have here is to view the date of last login by an Admin User. Additionally, you can search the Audit Logs where user is equal to <admin user> and retrieve all jobs associated to that user that have been executed or are currently being executed.
Also, 5.0 does allow you to search for User within the system. This returns a listing of items by User that might be beneficial to your needs.
Let me know if you have any other questions.
Lead Solutions Consultant