The service pack includes the following new functionality and feature improvements:
New Reports
• The new Site Activity report displays a report showing the data transfer between users and specific websites for any user.
Error Pages
• A new look and feel has been created for error pages.
• Error pages can be more easily customized and can include embedded objects.
Kerberos Authentication
• You can now use Kerberos authentication when you deploy an array using network load balancing (NLB).
Read the release notes: Forefront TMG Release Notes (SP2).
Download Details – Microsoft Download Center – Forefront TMG 2010 Service Pack 2