The download is here:
Note the caveat for remote administration of the SP1 integrated product:
In order to configure the new Hyper-V Server 2008 R2 SP1 feature settings (RemoteFX, Dynamic Memory), make sure to use the the latest Windows 7 SP1 Remote Server Administration Tool(RSAT) for the client or use Windows Server 2008 R2 SP1. The Windows 7 SP1 RSAT tool can be downloaded from here.
Note that the download is quite large so it may take a while:
We will blog about our experiences with setting up the revised version of Hyper-V Server 2008 R2 in the coming weeks. One of the first steps will be to stand up a cluster based on it.
Hat Tip: Susan Bradley
Microsoft Small Business Specialists
Co-Author: SBS 2008 Blueprint Book