For Server 2008
Open Server manager
Expand Active Directory Domain Services
expand the domain and follow Part B below.
For Server 2012
Click on Tools and select Active Directory Users and Computers
follow Part B below
Generally for both
click on start
Click on Administrative tool
click on Active Directory Users and Computers
Select the OU
Click on the User group and on the name of each user,
Select the Properties box
Here you can find the job titles.
Note: This can be performed as well using PowerShell commands