As an administrator of Barracuda Web Security Gateways for a university, you may have two groups of devices; one group for faculty and staff and another group for students. You want to allow Skype and Yahoo IM internally for faculty and staff, but not for students.
To configure: Click on the Barracuda Web Security Gateway group assigned to faculty and staff. From the web interface, you would set Allow for those applications on the BLOCK/ACCEPT > Applications page.
For the Barracuda Web Security Gateways filtering student traffic, you want to block those applications, but allow Googletalk. Click on the Barracuda Web Security Gateway group assigned to students. From the BLOCK/ACCEPT > Applications page you can configure these settings for the student group.
Additionally, your IT department may want to push Microsoft updates to student PCs, so, in the Updates section of the BLOCK/ACCEPT > Applications page, you might set Microsoft Updates to Block. However, the faculty and staff have admin rights to their PCs - you would set this value to Allow on that group.