Here it is. We have a new KB that details updates and hotfixes required for SCVMM, Hyper-V and Clustering. Read the article here.
I've commented on the hotfixes inline below, providing a Support Engineer's perspective.
Install these. No question.
950050 (http://support.microsoft.com/default.aspx?scid=kb;EN-US;950050/ ) Description of the update for the release version of the Hyper-V technology for Windows Server 2008
Note If these hotfixes are missing from a Hyper-V server, the System Center Virtual Machine Manager 2008 Admin Console lists the server status as Needs Attention. Hotfix 956774 should be installed on the Hyper-V servers and on System Center Virtual Machine Manager 2008 Server.
I would change this from 'Recommended' to 'Required' based on experience.
Install ALL hotfixes on ALL Hyper-V servers, whether SCVMM is involved or not. This is more than a recommendation based on cases I have worked.