The second service pack we are holding off on installing is Exchange 2007 Service Pack 2 on our SBS 2008 installs.
- Official SBS Blog: Microsoft Exchange 2007 SP2 installation is blocked on Windows SBS 2008.
- Microsoft Knowledgebase: KB973862: You cannot install Exchange Server 2007 Service Pack 2 on a Windows Small Business Server 2008-based computer.
While the KB article contains some content addressing things that break when Exchange 2007 SP2 gets installed on SBS 2008, there is no real need at this point to install the Service Pack.
Also, there will be an SBS 2008 specific Exchange Service Pack 2 package released at some point that will allow us to install the Service Pack without it breaking things.
Microsoft Small Business Specialists
Co-Author: SBS 2008 Blueprint Book