As I mentioned on my previous blog post, it is fine to install Windows 2008 R2 SP1 on machines running Forefront Threat Management Gateway (TMG) 2010 and Forefront Unified Access Gateway (UAG).
Yesterday ISA/TMG team blogged about this subject making an official statement: “TMG 2010 SP1 and UAG 2010 SP1 are fully compliant with the new Windows service pack. ”
Although, there are some points you should observe and order you should follow when planning deploy Service Pack 1 on TMG 2010:
1. Enterprise Management Servers (master and replicas – only for TMG deployments).
2. Array managers.
3. Array members.
Check ISA/TMG team blog post for more info.
That´s it! Plan, test and update!! In this very order